Printable Version of Topic

Posted by: tshih914 Feb 19 2023, 11:45 PM

My 1.8L 914-4 with stock Bosch L?-Jetronic FI after being stored several years started to develop a hard to start problem. When finally started would stall when I give the gas pedal any input to raise the revs. I suspect there was some kind of intake air leak and while fiddling around had a backfire which blew the AF meter which I had Pelicanparts repaired. After replacing the fuel lines with the stainless ones from Tangerine Racing and flushing out the fuel system with Techron the engine started to run normally for a short time. Now the engine can be started and fast idles at 3000 rpm but again any input to rev up the engine results in stalling. The idle adjustment screw at the base of the throttle housing is fully closed. Any suggestions on how to fix?

Posted by: Van B Feb 20 2023, 01:28 AM

Check to make sure your AFM is plugged in first.

Posted by: wonkipop Feb 20 2023, 01:38 AM

sort of sounds like its not connected maybe?
moving throttle plate takes throttle position switch off idle position and hands off to AFM.
except AFM might not be there.

check that first.
then troubleshooting step by step can commence.
sounds like this problem was already there before you had unfortunate backfire and wrecked the AFM. kind of pointing at maybe a problem in the harness? or somewhere in the hand off between the TPS and the AFM.
anyway its got to be done methodically.


fast idle is likely a separate problem. maybe.
one step at a time.
save that for later.

what 1.8. 74 or 75?

Posted by: Geezer914 Feb 20 2023, 06:48 AM

1+ on the AFM not being connected. Check for vacuum leaked. The intake boot may have a crack.

Posted by: tshih914 Feb 20 2023, 11:02 AM

I assure all that the AFM is plugged in and my fuel pressure gauge reads 28psi. One other piece of info is when the engine is "idling" at 3000 rpm I placed my hand to cover the nozzle of the air box housing feeling for vacuum from the air passing through the air filter into the AFM and felt little air flow! This means that there is an air leak (like when you adjust the idle by opening the screw at the base of the throttle to bypass the AFM). I had replaced the intake boot when the initial problems showed up. When searching for vacuum leaks there are lots of hoses and connections and even the O-ring gasket under the oil filler cap to check. Also is there an auxiliary air flow sensor in the 1974 1.8L FI system?

Posted by: dr914@autoatlanta.com Feb 20 2023, 11:17 AM

for the hell of it check the throttle body boot for cracks

Posted by: rhodyguy Feb 20 2023, 01:22 PM

Would a vacuum leak down stream of AFM result in a low idle not a high one?

Posted by: wonkipop Feb 20 2023, 02:17 PM

thats been my experience.
air leaks usually mean it won't idle at all or it will have an unsteady idle and hunts around. air leaks won't pull the AFM flap, so usually they lean out.

@http://www.914world.com/bbs2/index.php?showuser=4426

these are handy if you don't have them.
factory workshop manuals.

http://p914-6info.net/Manuals.htm

you may as well download them all (except 914/6 specific).
fuel injection = group 2.
has all the trouble shooting checks for each L jet component.
its a bit tricky to read as its mixed in the with D Jet stuff.

back to high idle, i suspect this is the decel valve.
its come up before with two other members.
fits the pattern. idle stuck at 3000 rpm.
i'd have to dig up the thread.
but @http://www.914world.com/bbs2/index.php?showuser=26011 can probably find it easily, he was the original poster for one of them.
or he can lay out the precise process for testing the decel valve to see if its good,
and also to adjust it. the decel valve is adjustable.
its diaphragm has probably stuck.
the air route through the decel valve will pull the AFM flap and let the ECU know its wanting the fuel to match the air. even though the throttle position switch is letting the ECU know the throttle is closed and at idle position. in other words it is perpetually stuck at halfway down from open throttle to closed throttle.


accurate vacuum hose layouts are here on page 3 of this thread.

http://www.914world.com/bbs2/index.php?showtopic=357407&st=40

for 74 models.
you can check your vacuum hose set up just to be sure.
but i don't think its going to be an air leak that is causing the high idle.

Posted by: wonkipop Feb 20 2023, 02:33 PM

there is no auxiliary air flow sensor in the L jet.
but there is a cold start aux air flow valve. AAV.
provides extra air to the engine during cold start.
but its connection is in the boot and after the AFM flap.
so it causes the AFM flap to deflect and for the car to receive extra air bypassing the closed throttle. there are two other sensors to measure temp. the main one at a cold start is the cylinder head temp sensor telling the ECU the engine is cold. i doubt the AAV will cause of the 3000 rpm high idle. it will raise the idle if its stuck open but not usually to that extent. not from stone cold anyway.

its a matter of downloading the manual and testing each component methodically 1 by 1.

i'm not sure exactly what is causing the engine to die when you gas it for revs.
apart from the AFM not communicating properly with the ECU.
i've got some other L jet diagnostic manuals. i'll look through them to see if thats a specific fault mentioned. as you mentioned - you had this fault initially before AFM explosion. so its something there you have not found yet despite the rebuilt AFM unit.

i don't want to speculate too far, but one of the components on the check list will the throttle position switch. i'd have to read further on what that might lead to if its faulty or not operating correctly.

Posted by: Van B Feb 20 2023, 02:51 PM

You covered the snorkel completely and the car kept running??

Here check this out to help you at least get a baseline on your connections:

https://youtu.be/ToxifurNXXg


https://www.youtube.com/watch?v=ToxifurNXXg

Posted by: Van B Feb 20 2023, 02:57 PM

@http://www.914world.com/bbs2/index.php?showuser=24231 What alerts me is the no change in idle with the snorkel completely covered. I made that video because this thread reminded me that I should post this up for future reference.

Let’s confirm connections first and then see what’s working and whats not.

@http://www.914world.com/bbs2/index.php?showuser=4426 , the high idle started after you made repairs to the car? You said in your original post that it ran normally for a bit. What happened between then and now?

Posted by: wonkipop Feb 20 2023, 03:20 PM

i read that as feeling around for airflow at snorkel rather than putting his hand over it and closing it off? engine should die if its closed off i agree.

nice little video. all there.
its an EC-B too.
with the vac advance line from distributor to throttle body.
EC-A won't have that. nor a 49 state 75. just the retard vac line in those.

Posted by: Van B Feb 20 2023, 03:33 PM

Yeah, I know, but I don’t care about California emissions lol

Posted by: wonkipop Feb 20 2023, 03:49 PM

just in case @http://www.914world.com/bbs2/index.php?showuser=4426 has got a retarded (nation of california) engine and sees a hose that isn't there thats been holding him back for 50 years.

we need to stick that video over in the 1.8 thread in originality.
its 101 L jet vac hoses for compleate idiots and 100% correct,
for idiots like me 5 years ago.

i noticed you carefully waved your hand in the general direction of the "dreaded"charcoal can!

Posted by: jim_hoyland Feb 20 2023, 03:52 PM

All the above; L-Jet requires that there are no vacuum leaks. I found the small hoses were first to go, even a T connecting them became brittle and broke.
To test the small hoses, try bending them between your fingers. That’s how I found the leaks.
Subsequently, I placed an in-line Vacuum gauge in one of the larger hoses

Posted by: wonkipop Feb 20 2023, 04:13 PM

@http://www.914world.com/bbs2/index.php?showuser=26011

thinking about his problem there are two tests he can do right now without fiddling with anything or altering things as they stand. given the engine starts and fast idles at 3000 rpm. its obviously getting fuel at crank and at idle. and plenty of air.

1. before starting check the operation of the throttle valve. move it around by hand and make sure it is moving freely and resting right back at closed position.

2. start it up and let it settle at its 3000 rpm.

3. clamp off the vac hose tightly shut between decel valve and intake plenum.
note what happens if anything. does idle change. (make sure you clamp the right hose, its the one that comes out of side of decel valve and goes to intake plenum EDIT - sorry it comes out of end of decel and goes to plenum - it operates the valve off vacuum, but thinking about it you can also clamp off the hose that comes off side as its getting the air from the intake boot, so either of those can be clamped off shut).

4. unclamp hose. let engine return to 3000 rpm if it did change.

5. clamp Aux Air Valve hose tightly shut between end of AAV and intake boot.
(clamp it before it gets to the Y junction into boot as you want to isolate the AAV. - the other hose off Y junction is going to the decel valve).
note what happens if anything. does idle change.

Refer excellent video by prof Van B of hoses posted above to know which hoses referred to.

report results of 3 and 5 back here.

------

Posted by: Van B Feb 20 2023, 04:24 PM

Boy does that all sound familiar.

I’d still like to know what changed from when it ran normal.

Posted by: wonkipop Feb 20 2023, 04:39 PM

it does sound a bit familiar, but not completely the same.

he said he left it to sit in storage for a few years.
something in there gave up the ghost during rip van winkle period.

they don't like sitting around.


EDIT - i seem to recall you ( @http://www.914world.com/bbs2/index.php?showuser=26011 ) got some weird thing where your 1.8 would run at 3000 rpm and not do anything else when you had something off. but its a couple of years ago and i can't find that thread anymore. maybe its my imagination and false memory? there was something i was asked to do by you and i think it was see if mine would start and run without the AFM plug in. mine would not. but yours would? and it was the way the fuel pump in yours had been wired in after moving to the front. mine is still stock and fuel pump is run off the AFM contacts after cranking phase. i could have this wrong. but yours would run and it ran at 3000 rpm? until you hit the throttle. my memory is not that good.

EDIT EDIT - can you see where i am going with this @http://www.914world.com/bbs2/index.php?showuser=26011 ?
we have to find your thread again and go through it.

Posted by: wonkipop Feb 20 2023, 05:11 PM

BTW @http://www.914world.com/bbs2/index.php?showuser=4426 - thats not the fuel pressure test for L jets.
you are going to find the correct test in the links to the manuals i posted previous.
you are actually looking for 35ilbs pressure when you operate the AFM flap.
its all in the manual. you can also test flow which is important as well as pressure.
again all the manual. but that is jumping ahead at this stage.
you need those manuals. the fuel pressure regulator is non adjustable in the L jets.

Posted by: Van B Feb 20 2023, 06:45 PM

@http://www.914world.com/bbs2/index.php?showuser=24231 . What he described is exactly what happened when I started the car and forgot to plug in the AFM. Steve tried it and the same thing happened for him. You tried it and it didn’t work. That’s when I realized my fuel pump wiring was wrong as yours was OE and Steve and I had a different setup from the relocation to the front.

Posted by: wonkipop Feb 20 2023, 06:52 PM

yeah -
see my post above where i edited it. memory recall was coming back.
i'm getting old and my ECU is a bit hard to fire up.
but i was remembering you did something exactly like this.

i'm thinking his pump wiring is letting the engine run because it does not need the AFM contacts operating at idle to do it.

and i'm thinking that maybe his EFI plug and harness from AFM to ECU is possibly kaput.
like despite being plugged in its not actually connecting.
so as you gas it its all over. all air and suddenly no fuel.
the ECU is not opening the injectors. no signal?

would pull those plugs out at both ECU and AFM and given them a good clean first of all.
checking for corrosion. then i guess test it all as per factory manual.

Posted by: wonkipop Feb 20 2023, 06:56 PM

@http://www.914world.com/bbs2/index.php?showuser=26011

which is to say as i suspected that high idle at start is not directly connected to his other problem. yeah its running at idle and weird but if it was factory set up it would not run at all. which is his real problem. if i recall correctly what mine did with plug out was fire up into life and then die immediately. as you would expect with original wiring of fuel pump to only run on crank and then hand off to AFM as soon as it fires and moves the flap, just that little bit that opens the fuel pump contacts.

which is why i think its not a vac leak that is his problem. (though never say never completely).

the real symptom to investigate in a trouble shooting manual is --->starts, then immediately dies and will not idle. as is noted in original post as the first sign of trouble some time back--------> before undertaking additional work? on fuel system? etc.

question for @http://www.914world.com/bbs2/index.php?showuser=4426 did you do anything to fuel pump in your work doing fuel lines after the problem initially presented with difficult start?

Posted by: Geezer914 Feb 20 2023, 07:13 PM

Go to Jeff Bowlsby's web site
and get the Ljet fuel injection wire harness diagrams. Get a test light and check the continuity of the wire harnesses.

Posted by: porschetub Feb 20 2023, 08:34 PM

reckon the only thing that will cause that is a sticking air gate in the AFM,most normal air leaks will cause a high idle of say 1500 but generally not more but not 3000.
I had this with one of my old BMW's after top overhaul and found the AFM was full of crap,run great after a good clean,same system but the 914 AFM is known to suffer issues after backfire of I'am thinking that's happened.
Cheers.

Posted by: JeffBowlsby Feb 20 2023, 11:58 PM

You might also check the quality of the contacts in the harness connector to the AFM. Bent? Gapped? Corroded/dirty? It’s very common for the old original contacts to be worn out by now, negatively affecting connectivity . The contacts are two cantilever springs that separate due to 50 years of metal fatigue, in addition to dirt, corrosion and others contamination causing deteriorated connectivity.

Posted by: wonkipop Feb 21 2023, 02:57 AM

yeah though this is even weirder and its something @http://www.914world.com/bbs2/index.php?showuser=26011 discovered.

it could be internal to the AFM like dirt, corrosion.wear on contacts etc.
but @http://www.914world.com/bbs2/index.php?showuser=4426 does have a new/rebuilt AFM now. i would think its probably pretty ok in those terms.

@http://www.914world.com/bbs2/index.php?showuser=26011 is on to this one i think.

if there was ever an argument for preserving a car in original condition - and by this i mean technically, not just aesthetically, it was during his relentless program to get his 1.8 running right. he knew i had a pretty unmolested car. so he kept giving me scenarios to try on mine. we didn't get the same outcomes. eventually between us all we cracked the fuel pump wiring trickery.

it sure is weird. but if that fuel pump is wired to the ignition circuit and it stays on, the car will run with the AFM disconnected from the ECU. but only with the TPS closed in idle position. no other position. and however it does it, it runs it at elevated revs.

and if its factory original wiring to fuel pump it won't run. it will fire, but it won't continue to run.

Posted by: wonkipop Feb 21 2023, 03:05 AM

yes.
and you are the man who would know.

Posted by: tshih914 Feb 22 2023, 07:36 PM

@http://www.914world.com/bbs2/index.php?showuser=24231

When I pinched off either one of the 2 hoses from the decel valve to the intake plenum the idle dropped from 3000 to closer to 1000 rpm. (result of 3)

The idle also dropped when AAV hose was clamped (result of 5.)


Attached thumbnail(s)

Posted by: Van B Feb 22 2023, 08:19 PM

Whatever you have back there by the batter near where the decel valve should be is not the correct part. If that thing is opening at idle, it will surely cause a high idle.

Edit: here is a thread of mine about the decel valve.
http://www.914world.com/bbs2/index.php?s=&showtopic=356522&view=findpost&p=2956383

Leave the Aux Air Regulator/Valve alone for now as it should be open until the engine is warm.
But if what I’m seeing back there on your second picture is the AAV setup, its a hot mess and probably a big part of your problem.

Posted by: tshih914 Feb 23 2023, 04:46 AM

@http://www.914world.com/bbs2/index.php?showuser=8571 B
Lol the hot mess near the battery is indeed not stock. When I replaced the fuel lines I used the braided hoses to connect the steel lines in the tunnel to the non-stock metal fuel filter inline to the remnant plastic line feeding the engine fuel rails (temporary hook up since I intend to stick a 2L rebuilt engine when done in place of the 1.8L currently in place). That mess is not any vacuum hose causing/relating to my high idle issue.

Posted by: Van B Feb 23 2023, 05:54 AM

Ok. Glad that thing wasn't some decel valve rip off. So, what you can do next is take off the decel valve and adjust it. I went through that in the thread I posted the link to. You just need a vacuum gauge.

Posted by: Geezer914 Feb 23 2023, 08:45 AM

Got rid of all that shit, the decel valve and the charcoal canister.. Just have a hose from the oil fill neck to the throttle body boot and kept the auxiliary air valve.

Posted by: rjames Feb 23 2023, 11:50 AM

Keep the decel valve as long as it's functional and you can set it properly. It should help extend the life of the MPS diaphragm.

Posted by: wonkipop Feb 23 2023, 11:54 AM

no mps in a L-jet. so decel is not as critical as it is in D jet.

however agree with you, there is no need to get rid of the decel valve.
@http://www.914world.com/bbs2/index.php?showuser=8571 B has successfully adjusted one to the correct level.

but this is not his real problem?
his problem is the car only starts and runs at this idle level and dies as soon as he gases it.

the decel valve is elevating the idle level for sure.
if it was adjusted correctly idle would drop.
but.......it would still have the problem of not running once the tps switch comes off idle.

test would appear to indicate that the AAV is working as it should. maybe.
i imagine the engine was still cold when he did this test for us.
eventually it would probably have closed and the 3000 rpm would have dropped slightly. later on he can test his AAV to make sure its closing properly.
but not critical at this stage.
its not his real problem.

he can now move on to the next test which i have described in further post.

Posted by: rhodyguy Feb 23 2023, 11:58 AM

Curious. What kind of condition are the oil fill tower gaskets in? Replaced?

Posted by: wonkipop Feb 23 2023, 12:00 PM

ok @http://www.914world.com/bbs2/index.php?showuser=4426

@http://www.914world.com/bbs2/index.php?showuser=26011 (i'm sure) and i would like you to do one more test.

pull the AFM plug out (you can pull it out up at the AFM unit on the aircleaner) and see it if starts and runs at this 3000 rpm. don't touch the gas pedal. just let it start on its own.

if it does start and run do a second thing.

turn if off, restart it without touching the gas pedal or throttle and then once its running again at this steady 3000 open the throttle to give it the gas and see what happens. again with AFM plug out.

report back on the result.
-------


thanks for including the photos.
i am studying them trying to look at area between battery and firewall.
it looks like your ECU is not securely fixed but floating around in there.
its been rotated 90 degrees.
not that its necessarily the cause of your problem,
but @http://www.914world.com/bbs2/index.php?showuser=26011 (and i) are thinking of your ECU to AFM connection.
the test i have asked you to do is going to see if this is the problem.


-------

i can see from photos how you have rigged up the fuel lines.
looks fine. i can see most of your vacuum lines and they look right and looks like you have gone over them. i can even see the intake runners appear to have new or good condition woven seals. so all that looks pretty good for being tight and leak free.

its a good idea inserting a full flow high pressure fuel filter in the line like you have.
i have one too which i have installed in almost the same spot.
will save your injectors if you have a newer type fuel pump and it detonates internally.

which leads to the next question.

when this problem of more and more difficult starting first was happening, where was the fuel pump and what was it. original type pump under engine bay on rhs? with original electrical connection?

and did you install a new fuel pump with all your work on the fuel lines.
if you did, where is it, what type and how is it wired in to run?

Posted by: Van B Feb 23 2023, 02:50 PM

@http://www.914world.com/bbs2/index.php?showuser=24231 if the decel valve is full flow, it could still make the car stall as soon as he touches the gas because you're just introducing even more air into an already excessively lean scenario.

that said, I agree that this symptom is way to similar to what we learned about how the engine acts when the AFM is unplugged/dead and the fuel pump is DAPO wired.

Posted by: wonkipop Feb 23 2023, 03:58 PM

yes agree re the decel valve/lean scenario.

test i have suggested is another easy one to do without jiggling or mucking about with anything much.

just methodically ticking it off.

he should definitely go and adjust the decel valve following your instructions in thread you linked to. but before he takes if off and does that, just to run this test.

and tell us how the fuel pump is wired.

it won't exactly nail it down to the ECU connection.
but i'm thinking about how he reported the problem initially arising.
progressively more difficult starting.
then it dying when he gassed it.
to me this is the real problem he has?
that could point to either poor contacts in the AFM unit itself or a dodgy ECU/AFM connection. progressive degeneration of an electrical contact? he has a new AFM now, so its unlikely to be internal to that.
but the other two parts could still be the issue.

he has subsequently done more work on the fuel system.
so now it appears to start ok, but run only at idle.
so something did change.
we both know how that can happen if the fuel pump is not wired OE.
it can and will start easily. with that plug out. when it should not.
but it won't do much else.
i guess i am interested in whether his work in between has resulted in this easier start.
but thats all its resulted in. and its a bit of a smokescreen.

and perhaps most importantly in between these two states of affairs it seems it ran fine for a while!!!

lets see.

i'm also looking at that ECU which is very evident in photos to be in a less than desirable state of affairs. perhaps he has just disconnected its mounting as he undertakes this work. but its not great.

---------

after he reports back we could also get him to run an easy test on the decel to explore your suggestion. even before he adjusts it he could take it out of the equation by pulling the hoses out of it. and plugging the hoses. it should still start i think, even without all that air its getting from the decel - but start and idle lower.
he can then give the throttle a tweak and see what happens. ie does it die once it comes off TPS or will it respond to throttle and not die.

but i am thinking one step at a time.

do test i suggest above in previous post first.

then do the decel valve delete test second.

Posted by: wonkipop Feb 23 2023, 06:50 PM

ok
@http://www.914world.com/bbs2/index.php?showuser=26011 and @http://www.914world.com/bbs2/index.php?showuser=4426

i found Van's topic regarding the way the car will run with the AFM plug out.

link to the page.
goes over next 3 pages.

http://www.914world.com/bbs2/index.php?showtopic=356678&st=320


mine with OE wiring of fuel pump (runs when cranking and then runs off AFM flap which moves enough at idle to open the fuel pump contacts) would crank and fire and run for about 10 seconds from a cold start. conclusion was it was running off cold start injector.
after that on repeated starts it would crank, fire for a second and die.


starbear's with non OE wiring of fuel pump (pump on whenever ignition on).
good condition AAV. good condition decel.
would crank, fire and run but die after a longer period of time than mine.
repeated starts led to repeat of cycle except it ran at idle on its own for longer each time with revs gradually rising.
eventually getting out to running for 40 seconds.


van's with non OE wiring of fuel pump similar to starbear.
started with high idle (1400). slowly rose to 2000 rpm this was when the car was still suffering from a poor low idle at cold due to the non functioning AAV. but after a non functioning decel valve had been corrected. ran happily at high idle. van blipped throttle and it died. started it a second time and it repeated the effort.
van noticed the next day his AFM plug was out. plugged it back in and car started normally with its usual poor/low idle from cold.

as a result of this accident, wonki and starbear were asked to see if they could repeat what van's car did. see results above.

from this we worked out that if the ignition circuit was running the fuel pump an L jet would start and run in a strange way without the AFM plug. but only if the ignition circuit was running the fuel pump. wonki car with OEM wiring needed the hand off between the cranking circuit running the f p to the AFM flap which kicked forward and opened the contacts to run the fuel pump. no hand off with the plug out. so it dies instantly.

none of them would run once you kicked the throttle open as all of them were looking for the AFM signal once the throttle comes off the throttle position switch at idle.

this is the condition we want to try and tick off the list for @http://www.914world.com/bbs2/index.php?showuser=4426 .
to do this we have to work out what is running the fuel pump at start up.
is it ignition circuit modification or is it still stock.

Posted by: tshih914 Feb 23 2023, 07:58 PM

Posted by: tshih914 Feb 23 2023, 08:16 PM

The fuel pump is the original one that came with the car. Its in the front of the car under the fuel tank next to the brake master cylinder protected by the steel panel that,s bolted to the A-arms front torsion bar area.
I unplugged the AFM and the engine started after several attempts and started to idle around 1200 rpm initially then rose to 2000 rpm. Shut it off and upon restart while at 2000rpm try to give it gas it immediately stall. All the while unplugged so no AFM input

Posted by: wonkipop Feb 23 2023, 09:01 PM

wow @http://www.914world.com/bbs2/index.php?showuser=4426

that was a quick test and reply.
we are making some progress.

first thing. fuel pump may be original or original type.
but its definitely not in stock position for a 74 L jet.

would appear its had the by now common modification of a move up to front of car under fuel tank to guard against vapor lock.
(the original stock position is right under the engine on right hand side tucked right up above the heater tube that goes into the longitudinal).

given the behaviour after you unplugged the afm its definitely not stock OEM wired in. i'd say its running off the ignition circuit.

i'd have to think about this a bit.
no doubt @http://www.914world.com/bbs2/index.php?showuser=26011 will come in again at some point.

but the behaviour with the AFM unplugged was not exactly the same as with it plugged in by the sounds of it. i would have expected it to be exactly the same if the fault or problem was that the AFM was not sending a signal and the car was just running off the fuel pump triggered by the ignition circuit and the throttle position switch at idle.

i'd probably think at this stage there was a signal getting through.

i'm going to go with the idea that the AFM signal is not a problem.

you should turn to the second test now.
pull the hoses off the decel valve and plug the hoses so it can't pull air.
try starting it. it should go. and idle should be reduced to level it was when you clamped the decel valve. but you might find the idle air screw is too closed and you might have to adjust that to get it to idle. its been getting a lot of air through that decel valve. but its not "leaking" air. it is actually metered air. it will have been pulling the AFM flap open. the AAV will have too. so this is not an unmetered air leak.

and then try gassing it after you have got it idling.
this should be a good test for @http://www.914world.com/bbs2/index.php?showuser=26011 's thinking its falling over because it leans right out the minute you open the throttle.
see what happens and let us know.

Posted by: Van B Feb 23 2023, 09:41 PM

Definitely sounds like the AFM is doing stuff… but also, you can’t have that idle screw all the way down. You won’t idle like that. Put it two turns out and leave it there till you’re ready to set it up correctly.

Ref the video I made for you, remove the vac hose on the decel valve that runs from the side of the valve to the manifold. Block off the manifold and the port on the decel valve. Leave everything else connected for the moment.

Give it a start and lets see how it behaves.

Also, please post up your door placard so, we can confirm your mfg date.

Posted by: tshih914 Feb 25 2023, 04:35 PM

Did as instructed I opened the idle adjustment screw 2 turns and after cranking a bit the engine started with a rough idle then stayed around 2000-2500 rpm. Again when gassed the rpm drops to almost stall but when I release the throttle it would idle back up to 2500 rpm. After 2 stabs of the throttle it finally stalled. I 've included the photos of the blocked off manifold T and side of Dcel valve along with the door label showing a Jan.1974 build date.


Attached thumbnail(s)

Posted by: tshih914 Feb 25 2023, 04:36 PM

Attached thumbnail(s)

Posted by: wonkipop Feb 25 2023, 05:56 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

we are getting somewhere.
this time it did not stall, it almost stalled, but did not stall.
it did try to do the transition to open throttle.
not very well. but it showed hopeful signs!

the first time you sealed off the decel hoses it dropped to 1000, much lower than the 2000-2500 with this test. that was because in the first test the idle screw was closed completely shut. the engine was getting a significant portion of its air from the decel valve. to the tune of about 2000 rpms worth. now some of that air that was being supplied by the decel for the elevated revs is being supplied by the idle air passage being opened up.

the auxiliary air valve is probably supplying some rpms worth going by the tests.
when you pinched that one shut in the earlier isolation test you said the rpm dropped but you did not say by how much. if it was in proper working order it would have been in the order of 400-500 rpm worth stone cold. getting less as it warmed up and closed.

from here you really have to go through each component one at a time and test them.
you will need that factory manual i gave link to in page 1 of this topic.
you only need section 1 (engine) and section 2 (EFI).

it will be interesting to hear from other members.
there are some very knowledgable L jet guys on the site.
@http://www.914world.com/bbs2/index.php?showuser=26011 will likely have something to say now that could be useful.

i'm going to think about it a bit more.


EDIT
thanks for the VIN label. its built the week before mine.
got the same brown interior.
when we get to the end of this and hopefully get the old girl running i'll ask a favour of you for some archival info, but not now, lets get her going.

Posted by: Van B Feb 25 2023, 06:45 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

The decel valve is on the other side. I can’t exactly see what you’ve done in the photo but I see an open hose. Is that coming from the aux air regulator?

Posted by: Van B Feb 25 2023, 06:49 PM

Yeah this is all wrong. You’ve got the wrong part. You capped off the Y where it attaches to the aux air valve/regulator inlet, but then left the AAV open… which is allowing unmetered air into the manifold.

You need to put all that back together.

Watch my video again and go over to the passenger side and find the decel valve. That’s what we’re trying to get capped off.

Posted by: wonkipop Feb 25 2023, 07:22 PM

@http://www.914world.com/bbs2/index.php?showuser=26011 .

i think he has got it right.
he seems to have removed the hose between the decel valve and the Y junction.
the route for air to be drawn into the decel valve.
and he has capped the decel valve and the Y junction.
which means the decel valve can't draw air and the boot is sealed.
thats if i am reading his photo correctly?

i don't see any uncapped hoses to plenum in the photo.
so long as he has taken the hose out i understand he has it should be isolating the decel and stopping the air route and not leaving anything open.

Posted by: wonkipop Feb 25 2023, 07:26 PM

i think he has pulled this hose out and capped the Y and decel at where it joined them.

Posted by: wonkipop Feb 25 2023, 07:44 PM

where i am going with my thinking @http://www.914world.com/bbs2/index.php?showuser=26011 is

1. to get this poor old girl to idle without either the decel valve or the AAV being part of the picture. neither are needed for normal warm idle.

2. to see if he can get a warm idle using the idle screw. at around 1000 rpm.

3. do the gassing thing.

trying to get this high idle thing out of the picture if possible.

realise there are a whole lot of things need for stable warm idle.
not least
correctly adjusted valves.
correctly set timing.

if it won't transition to opening the throttle from that state of warm idle.
well?
there is a few thoughts that come to mind.

also if he can't get it down to stable low warm idle and it starts to hunt around as you screw it down it could indicate there are some air leaks. and these will be unmetered air leaks. but want to get these "legit" air routes out of the picture because they are masking whether it will do a normal warm idle.

Posted by: Van B Feb 25 2023, 07:54 PM

Looks to me then like the decel valve is connected opposite of mine and he hasn’t unplugged the decel line to the manifold but rather the bridge line from the intake to the valve?

See my mark ups below and tell me if I’m seeing it right?

Also, there is kink in the small line.


Attached thumbnail(s)

Posted by: wonkipop Feb 25 2023, 08:29 PM

@http://www.914world.com/bbs2/index.php?showuser=26011 .

yes i noticed that kink in the small vac line to the decel.


i think he has only vac line 9 off. bridging line as you call it. and has capped off the connection points. so long as he only has that line off he is alright.

attached pic of set up for vac lines to decel.
but to be honest i don't think it matters which of the large lines you plug in either to side or end. the small line is opening the decel valve and letting the air through.
i think it can work either way, but before i say that i better double check.
(if yours is the other way around from diagram and attached photo it would tend to prove it does work either way, since your valve is operating beautifully anyway!! )
however most cars are rigged the way it is in the vac hose diagram.
attached example.
which appears to be how his is rigged.








EDIT
but you might be on to something there with the decel.
i can't really see in to his photo clearly enough.

@http://www.914world.com/bbs2/index.php?showuser=4426 , can you take a photo in close to the decel valve so we can see it really clearly.

Posted by: wonkipop Feb 25 2023, 08:56 PM

i just watched your video @http://www.914world.com/bbs2/index.php?showuser=26011 .
your decel is rigged right or at least same as diagrams and how it is normally done.

i'm looking at his and it looks the same.
from what i can see of it.
but it would be nice to see a close in photo just to be sure.

Posted by: r_towle Feb 25 2023, 09:03 PM

When I am hunting for a failure in the vacuum system, which has many parts, I remove all vacuum lines and tape over all the ports at the plenum.

This takes the vacuum out of the triage.
This also takes any hose out of triage.

Get the car running at idle (it needs no vacuum)
Add one vacuum line at a time, plugged into whatever device, properly.

Eventually you will create the issue again.

If you still have an issue after taking off all hoses and taping all ports closed, you could have an issue with a hole in the bottom of the plenum or your injector seals are leaking way too much.

Posted by: Van B Feb 25 2023, 09:19 PM

74 L-Jetronic needs the distributor vacuum for anything but idle at operating temp when setting timing.

I just realized we haven't confirmed the turns on his idle screw at the TB!

Posted by: wonkipop Feb 26 2023, 12:37 AM

he said he had it two turns out.
i imagine it was either already all the way down closed (which i think the introduction post said) or he at least turned it down to closed and backed it back up two full turns.

but i gather no further adjustment or attempt to bring idle down using it from there.

we probably will end up where r towle is suggesting we go!!!!

Posted by: nihil44 Feb 26 2023, 01:43 AM

I've come in late here and haven't read all of the posts.

Several times I have forgotten to replace the connector on the AFM with the result that it would start normally but stall as soon as you hit the gas. Similar symptoms as described in this post.

Secondly, I had a problem with the car stumbling when I went over a bumpy surface or railroad tracks. I discovered that, although the AFM appeared to be connected, the connector was not seating all the way home and was going intermittently open circuit when disturbed by the bumps

On exploration I discovered that the AFM connector has a rectangular foam rubber seal around the periphery of the row of 7 pin connectors to prevent water ingress but the seal was preventing the connector from fully seating. I removed the seal and the connector clicked fully home. Problem solved.

This might be worth a look

Posted by: wonkipop Feb 26 2023, 01:54 AM

yeah nihil we put him through that test - did not seem to be his problem.

good suggestion however to look at that seal.
his connector will be a 6 pin version.

ah. the joys of prehistoric EFI!

by the way, hows your car going mate?
got to get up to brizzy at some stage and drop in on you.

Posted by: Geezer914 Feb 26 2023, 06:12 AM

Last resort is to do a smoke test. Search on you tube on how to build one for under $20. You will find the vacuum leak.

Posted by: tshih914 Feb 26 2023, 07:57 AM

I have every vacuum hose hooked up the same as the diagram that wonkipop posted. My photo show the 2 plugged ports to the side of decel valve and the t leading to the boot (I will be ordering a new one from AutoAtlanta as the one currently in the car is an old used one from eBay that I got when the AFM explosion triggered the search for cause of stalling after starting). I have also removed the hose connecting the two ports
as instructed for this test. The idle adjustment screw at the base of the throttle valve was adjusted 2 turns from fully closed. I did mention that while the engine was idling at 2500-3000rpm I did try to cover the air filter box's snorkel with my hand and the engine did not stall indicating that there must be a vacuum leak. When I get the new boot installed I will hunt for the source of air leak with the Smoke in a can used to test fire alarm smoke detectors.
I just reattached the hose and started the engine after many cranks to get it idling at 2800 rpm before repeating test3 and 5 (wonkipop's earlier posts). When hose to side port of decel valve was pinched closed RPM dropped by 400-500 rpm. When AAV hose was pinched rpm dropped by 800-1000rpm. The smoke in a can wasn't useful in finding the source of air leaking pass the AFM pathway.

Posted by: Geezer914 Feb 26 2023, 09:39 AM

I had a hell of a time finding a vacuum leak. It wasn't until I did a smoke test, pumping smoke into the engine that I found it was leaking around the intake manifold gaskets. The hoses could be fine, it could be the injector seals. Do the proper smoke test, it will save you a lot of aggravation. On my engine, I ditched the decel vavle and the charcoal filter.

Posted by: Van B Feb 26 2023, 12:50 PM

Ok so, I checked my AFM to see what I settled on for screw turns after all my tuning before starting this rebuild. I have three turns out on the AFM airscrew and 1-1/4 turns out at the throttle body.
Every car will be a little different, but you should be in that ballpark as a baseline.

Posted by: wonkipop Feb 26 2023, 12:53 PM

ok thats interesting @http://www.914world.com/bbs2/index.php?showuser=4426 about the snorkel.
it wasn't clear to me whether you just had your hand near the snorkel feeling for air flow or had you actually blocked it off.

yes the engine should die if you fully block the snorkel.

positives so far.
you definitely have a farked up decel.
it might come back to life with an adjustment.
if it doesn't you might still be able to source one but they are hard to get hold of.
or you can do a decel delete.

for clarification when you first did the tests i suggested, you reported the opposite results. decel dropped it by about a 1000 rpm from 3000 to 2000. AAV drop was less.
you did not give a specific number but described it as less than the 1000 drop due to the decel.
EDIT correction. went back and read the first test results. decel was 3000 to 1000. drop was 2000 revs.
AAV drop was less.

this repeat of the test seems to be the other way around/different?

guessing difference in part is due to you having the t/b idle screw out on this second test?

----

i think both of these components need to come off and be tested.

onward looking for more.

do the second smoke test.

i would also suggest a proper f p test.
i think i can see you still have your fp gauge plumbed in.
and its in the circuit before the regulator? which is good.
so you can do this test now fairly easily.
when its running you either pull and plug the vac hose into the back of the regulator or just pinch it tightly shut. the fuel pressure should be 35+/-. with the hose back in or the clamp taken off it should fall to 28. i know you have tested it and got 28. but that would have been the vac hose on value. be good info to know if its building the full pressure thats needed to acceleration/load phase.

Posted by: Van B Feb 26 2023, 12:58 PM

The AAV is designed to increase idle by that amount until the engine reaches operating temperature. So, nothing revealing there just yet. I think the aspect that should be focused on right now is the non-response to throttle input.

I’ll tell you that in getting my L-Jet sorted, I replaced every old hose on that entire topside. My car was very original but what had been replaced wasn’t exactly the right size most times. Belmetric has almost all the correct hoses at a good price and wonki has provided you with his artisan diagram that I just love!

We also need to consider your fuel injectors are full of garbage and not spraying correctly or at all. Have you looked at plugs?

Posted by: wonkipop Feb 26 2023, 12:58 PM

ps
in addition to blocking off snorkel the only other way it could pull air into the air cleaner is via the hose from the charcoal can to the air cleaner. i can see that hose is either very badly frayed in center or somehow joined. not clear. if that hose has leaks in it it could pull air via that into the a/c despite you having your hand over the snorkel.

maybe it can even pull air through the charcoal can?
anyway if i close off my cars snorkel with my hand it will die. but its not running at 3000 rpm either when i do it.

if you wanted to take that hose out of the picture for now you could pull it out of the aircleaner and plug the port on the airbox.

Posted by: Van B Feb 26 2023, 01:00 PM

Yes. All these hot garbage hoses need to be fixed or else we’re shooting in the dark and wasting time.

Posted by: wonkipop Feb 26 2023, 01:03 PM

bit by bit we are heading towards the Van B/wonki situation.

you ended up doing everything and checking everything on the EFI system as you went.
i did all of mine before we even attempted a start. the whole lot. after a 16 year sleep.
but i had mike looking over my shoulder. do this. etc. now do that. and on.
injectors, injector seals, hoses, distributor operation, ......on and on.

anyway, it should be solvable. trial and error. tick off the bits one by one.

Posted by: wonkipop Feb 26 2023, 01:58 PM

two suggestions by other members re injector seals.
sensible suggestion.
i did mine after the sleep along with new injectors.

put them on your list to get some if you haven't done them.

another thing to get hold of is a throttle body to plenum gasket.
914 rubber has them.
worthwhile replacing that regardless. they do go hard with age.
pretty cheap little part so its not a heavy investment.

and another suggestion the plenum itself can corrode and have pinholes in it is very true.
they will likely be underneath and very had to see without getting it off.
bit of a job. notice there is a bit of surface corrosion on the intake runners.
so its a possibility.
smoke test should find them however if they are there.

Posted by: tshih914 Feb 26 2023, 03:23 PM

Considering all recent suggestions my plan going forward is
1) replace all hoses with new (Someone posted that Belmetric sells all hoses but when I looked at their website the search under vacuum hoses gave no results) I also need to know if someone sells a complete kit that allows complete replacement of all vacuum hoses for the 1.8L L-jet (at least list the correct id and length of each hose needed.)
2) replace FI boot (already ordered from AutoAtlanta)
3)replace throttle body to plenum gasket from 914 rubber
4)fuel injectors appear to be fine as the engine was running fine and idled at 3000 rpm so may replace the injector seals which are old.
5) measure the Fuel pressure and adjust the running pressure on FP regulator 35psi and 28 psi
6) systematically go and check/test each component as per factory manual

Posted by: wonkipop Feb 26 2023, 03:50 PM

check auto atlanta if you want a convenient vac hose kit.
i believe you specify your model when ticking the box and get all the right hoses right length.

the fuel pressure regulator on the 1.8 is non adjustable unlike the earlier D jet ones.
if its not working right its a new regulator. but don't necessarily blame the regulator just yet. check the values. it might also be that the fuel pump is not delivering sufficient pressure. i rebuilt my original fuel pump completely from top to bottom (its not supposed to be serviceable apparently but the germans forgot australians love to take things apart and make them work when its not supposed to be possible). at the end of that i tested the fuel pump independantly of the car to make sure it was making pressure and also tested flow. i was making 38 ibs out of the rebuilt pump and got the spec flow rate (delivery volume over a timed period). so insufficient fuel pressure can be down to a weak worn out old pump. basically the regulator bleeds off some of that pressure the pump makes to take it down to 28 lbs at idle. but there is no adjustment nut on the correct 1.8 fp regulator.

Posted by: wonkipop Feb 26 2023, 03:58 PM

direct link to AA vac hose kit.

http://www.autoatlanta.com/Porsche-Vacuum-Line-Kit-1-8-914-Parts-PN-BAAVACKIT2.html

(it was under accessories section, not hard parts, and was listed in engine misc.)

Posted by: tshih914 Feb 26 2023, 05:18 PM

I just ordered that kit but it says the kit doesn't include the 19mm hose. So Where do I get the 19mm hose (where does this hose connect? the charcoal cannister?)

Posted by: nihil44 Feb 26 2023, 05:47 PM

Here is the gasket on the AFM connector which wasn't allowing connector to seat home fully.

Posted by: nihil44 Feb 26 2023, 06:28 PM

I have been pursuing running issues and vac leaks for the past 8 months. I have used smoke machine, compressed air (as recommended by factory - Bowlsby website for this) and vacuum from a vacuum pump and a vacuum cleaner

Smoke machine:- I made one from PVC plumbing fixtures as in a few YouTube websites. Worked ok but the smoke went everywhere, it lingered in the engine compartment and it was not easy to see just where the smoke was coming from. Also, I had the machine going for too long, it overheated and melted some of the PVC - result one buggered smoke machine

Vacuum pump hand held: - intake chamber volume too large for pump and unable to pull a vacuum

Vacuum cleaner:- very simple construction. 6omm OD pvc plumbing pipe with end cap glued to pipe. Hole in end cap of a size to accommodate a grommet and the vacuum cleaner nozzle










I used kid's bubble mix liquid diluted with a little water into a squirt bottle, applied and waited for the bubbles to appear

Compressed air:- same construction as above except in place of the grommet on the end cap I used a schrader valve to connect to the compressed air via an adjustqable regulator





Some of the results:-

Small crack in the neck of the oil filler tower. George Hussey says in listing for this item used, that they always break. I had to get underneath with a mirror to find that one



Both inlet manifold gaskets had cracks in them. One obviously had a washer embedded in it which caused the crack





I bought a set of Victor Reinz gaskets which are phenolic resin with a thin gasket material applied to both sides. I fitted them and just to be sure I re tested them for vac leaks and sure enough, one side leaked. So I put a thin universal gasket on both sides of the gasket but the overall thickness was too much and I couldn't do up the nuts on to the studs. I ended up compromising by putting the thin gasket on just one side and this is working

Victor Reinz standard gasket. Note how thin the gasket facing material is

Posted by: wonkipop Feb 26 2023, 06:36 PM

short answer is you cannot get the 19mm hose.
though PET and my measurements say its 20mm ID. splitting hairs i know.
its the hose from the oil filler tower PCV valve to the air intake boot.
originally a formed hose to make the S curve.
people have had to do all sorts of subs and use all sorts of different hose.
you will notice on your car it has already been rigged up as elbows to solve the problem of doing the curves and sealing the junctions.
that set up you have is probably ok. if you are worried about it keep the elbows and sub new hose. probably have to find rubber hose that is hydrocarbon resistant.

Posted by: wonkipop Feb 26 2023, 06:39 PM

love your work @http://www.914world.com/bbs2/index.php?showuser=14058

Posted by: tshih914 Feb 27 2023, 09:45 PM

Thanks @http://www.914world.com/bbs2/index.php?showuser=24231 I do remember the old S hose was shot and I replaced it using the elbows. I went back to check the fuel pressure once I got it to start and idle at 2800 rpm. The gauge reads 28psi with vacuum hose connected and when pinched close reads 38psi so my fuel pump is working correctly.

Thanks @http://www.914world.com/bbs2/index.php?showuser=14058 for the compress air setup. I may try that.

@VanB how do you adjust the AFM (you mentioned 1-1/4 turns out in the throttle idle adjuster screw and AFM screw was 3 turns out.) Where is this screw on the AFM located?

Posted by: wonkipop Feb 28 2023, 02:26 AM

@http://www.914world.com/bbs2/index.php?showuser=4426
beaudy. at least we can tick off the fp as A O K.
regulator and pump.

Posted by: Van B Feb 28 2023, 06:51 AM

See the little hole near the front right off the AFM? That's your air bypass screw.


Attached thumbnail(s)

Posted by: tshih914 Feb 28 2023, 07:44 PM

Thanks, now for my case is there any point in messing with that screw when it appears I already have some air bypassing the AFM?

Also since my decel valve appears to be farked up and there are no replacements has anyone opened one up to see if they can repair the damage?

Posted by: wonkipop Feb 28 2023, 07:51 PM

i probably wouldn't play with it at this stage.
its a new rebuilt AFM and theoretically should be about right.
but then again @http://www.914world.com/bbs2/index.php?showuser=26011 might have something to say.

i have never had to fool with mine.

i don't think you can open a decel.
its the sort of thing i would do of course.
attacking a fuel pump was a lot of fun.
but only with a spare to replace it.
i take the attitude destruction is likely.
i kind of looks like it would be pretty hard to get back together.
however there is a guy in australia who apparently rebuilds these things and other vac devices and has proper equipment to open up the crimping seams etc.
if it is farked up and won't respond to adjustment it will very likely be the diaphragm that is rat sh#t. so its pretty hard to fix unless you feel like becoming one of those kinds of experts.

Posted by: Van B Feb 28 2023, 08:07 PM

Have you adjusted the decel valve or tested it to see what vacuum its opening at?

Also, they are still out there. You just gotta know what to look for:
https://www.ebay.com/itm/403375849459

Posted by: Van B Feb 28 2023, 08:09 PM

@http://www.914world.com/bbs2/index.php?showuser=24231 quit being so scared to that mean AFM. All he needs to do is confirm how many turns out he is on the bypass screw… we’re just confirming baselines on the system.

Posted by: tshih914 Feb 28 2023, 08:47 PM

Just for the hell of it I google search " schematic of Bosch L-Jetronic decel valve" and came up with hit on last years' 914world post

http://www.914world.com/bbs2/index.php?showtopic=342479

Read all 3 pages and it appears that a 911 decel valve may be usable as a last resort. but the tests for proper function is given by GregAmy:

Testing the decel valve is fairly straightforward. With no vacuum on the port, the valve should be closed and you can't blow through it. Adding a vacuum via a Mity-Vac and the valve should open and you can blow through it. As I recall the desired setting for that cutover is 17mmHg?

If you can blow through it when it's off the car, and/or cannot blow through it with vacuum on it, then it's bad and/or out of adjustment. I wouln'dt be surprised if a prior owner danked around with the adjustment...

If it works fine but the cutover vacuum is either too high or too low, then it can be adjusted via that locknut and screw to ~17mmHg.

What are your current symptoms when testing in this manner?



Attached image(s)

Posted by: Van B Feb 28 2023, 08:53 PM

Thats too low IMO. I posted the link to my thread on post #29 on your thread here.

Posted by: r_towle Feb 28 2023, 08:57 PM

Ever check the boot after installing the afm?

Posted by: tshih914 Feb 28 2023, 09:10 PM

I wonder what is the diaphram (redline in schematic) made of rubber or metal? If rubber then age will lead to hardening and cracking

Posted by: tshih914 Feb 28 2023, 09:13 PM

No I have a new one coming from AutoAtlanta that I will install along with new hoses and gaskets

Posted by: Van B Feb 28 2023, 09:58 PM

Diaphragm is rubber. It gets hard and less flexible, but the spring is what wears out and what causes the required adjustment. Lots of movement and heat cycles over the years.

If you’ve read my thread, I was having high idle issues when running and idle hang when driving.

IMO, you have a whole collection of maintenance issues from deferred maintenance over the years. None major or you wouldn’t even get a high idle and smooth running.

I think your biggest issue is it not taking throttle input.

Posted by: wonkipop Feb 28 2023, 10:23 PM

its the only bit i am genuinely terrified of.

the rest of it i just tear into it.

agree with you, this poor baby has a ton of deferred maint. items that have all built up.
and its been tweaked along the way at various points to make it idle /whatever.
its finally accumulated to be "all too much" for it.
progress can be made when all hoses/seals are verified as non leaking and associated vac/electrical "gadgets"/ignition items tested and confirmed as spec operational.

Posted by: wonkipop Feb 28 2023, 10:40 PM

yeah @http://www.914world.com/bbs2/index.php?showuser=4426 . i am the guy with the last post who has found himself a 911 decel valve. it is indeed perfectly useable. you just adjust it to the vac levels with Van B's research info as a base to set it to, and adjust if necessary after test driving.

the only difference in the decel valves is that the 911 ones may have been adjusted to a different vac level than 914 and they had the bracket brazed on a different angle.

i still have not done an install of my 911 decel, as i run it without the decel.
i actually have a fuel pressure valve subbed in and all the hoses run to it.
this is the same as blocking all the hoses off except it looks legit.
i think the first owner installed it back in the day as a state of maryland emissions cheat.

i enjoy the way the car snaps off throttle.
there is no danger of a backfire through the induction system with the car properly timed and tuned. the most it does is drop unburned fuel into the exhaust system and i hear soft bangs and burbles out the muffler. the unburned fuel goes off in the hot muffler.

very occasionally if i give it a bit of stick and fiddle the clutch as i am manouvring out of my "garage" down over my "non cross-over" 19 th century bluestone curb it will momentarily die for about 1 second and then burst back into life. the AFM flapper has bounced back beyond the fuel pump contacts and it cuts the fuel until it resumes position. decel valve in part is designed to stop that - slows and cushions the return of the AFM flapper back to near closed - as well as being a useful emission device to stop pathetic juvenile minds like mine being amused by exhaust pops and dumped hydrocarbons.

that only applies to L jets. i hear the decel is a little more essential to the long life of one highly desirable and difficult to procure part in the D jet set ups.

Posted by: wonkipop Mar 2 2023, 09:55 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

i knew i had this filed away but couldn't find it my L jetronic files.
eventually stumbled on it again.

could be helpful.







combine this with the factory w/shop manual.

Posted by: wonkipop Mar 2 2023, 10:15 PM

here is the rest of it.
its an idiots guide.
which i was 5 years ago and likely still am.

Posted by: tshih914 Mar 3 2023, 10:11 PM

Well the new boot and throttle gasket was delivered yesterday so I replaced the old today. I also noticed that my air filter was badly mangled at one edge but after I replaced it with new one no difference in engine response to gassing it(stalls).[attachmentid=868336]


Attached thumbnail(s)

Posted by: tshih914 Mar 3 2023, 10:12 PM

Attached thumbnail(s)

Posted by: tshih914 Mar 3 2023, 10:13 PM

Attached thumbnail(s)

Posted by: tshih914 Mar 3 2023, 10:18 PM

When after many attempts to fire up the engine starts to idle at 3000rpm. I pinched off the Aux air valve and the rpm dropped to 1200, when I release the clamp the idle goes back to 3000. When I put my hand over the snorkel I feel no air moving into the AFM (its adjustment screw is covered by a rubber plug to discourage tampering after it was rebuilt.

Posted by: Van B Mar 3 2023, 10:42 PM

When you pinch the AAV hose, and the rpm drops to 1200, does the car take throttle? Or does it still stall?
Also, when you’re doing all this have you ever let the car warm up to operating temp?

Posted by: Van B Mar 3 2023, 10:43 PM

One other thing, I’m not understanding how you just noticed the air filter, I thought we talked to you about pushing the afm flap with the key on to see if your fuel pump kicks on?

Posted by: wonkipop Mar 4 2023, 02:57 AM

mangled air filter makes no difference to this scenario.
air filter is before the AFM!!!!
your problems are after it.
in airleaks. in the electronics. or the cuckoo clock analogue devices that mate with the electronics. its actually pretty dumb and quite accessible if you are methodical.
it will turn out to be simple. you just have to find it by careful searching.

you can suck in dirt for sure through a screwed air filter.
but....makes no difference to the current crisis.

read the stuff and get a grasp of L jet.
just a basic grasp.
you are an american. thats what americans do.
aussies just try and emulate.

then we can get cracking.
Van's your man to guide you through.

don't do anything random or think random thoughts.

if you are going to do this yourself you have to know what each element does.
its not that hard. if you ask me its more simple than a carb.
just work out what you think each thing does.
and ask questions.
get a grip on each part in the system.
just be an idiot (iggy pop claimed he was and look at him) and ask like an idiot if you have to.
no shame.

Posted by: Van B Mar 4 2023, 09:42 AM

Thanks for the vote of confidence @http://www.914world.com/bbs2/index.php?showuser=24231 . I was definitely in that boat in Oct 21 when I got this car and you were one of my mentors then.

I know his AAV needs a good cleaning, but since it’s metered air, I still remain more perplexed by why it won’t take throttle?

Posted by: Van B Mar 4 2023, 09:44 AM

@http://www.914world.com/bbs2/index.php?showuser=4426 . You should post a video so we can see and hear for ourselves.

Also, as a reminder, what do the plugs looks like? For each cylinder?

Posted by: tshih914 Mar 4 2023, 12:37 PM

Car does not take throttle it stalls

Tried it before and after warming to operating temp. same result.

Posted by: tshih914 Mar 4 2023, 12:46 PM

I only looked at plug under the snorkel it was running rich as I was cranking and cranking initially to get the engine to start (probably flooded until repeated cranking gave way to correct starting mixture.

I did not check for fuel pump running when AFM gate is depressed

Posted by: wonkipop Mar 4 2023, 01:05 PM

so am i.

coud be the throttle position switch?
could be the distributor. not advancing? clagged points. etc
could even be some kind of ignition system / EFI harness gremlin?
could be further undetected air leaks he has not found yet.


@http://www.914world.com/bbs2/index.php?showuser=4426 needs to progressively eliminate items on the checklist but also take known items out of the system we have already detected that are defective and don't need to be there for now.

1. fuel pressure has been confirmed as in spec and good.

2. decel is defective. eliminate it from system for now. plug hoses.

3. AAV may not be closing. but is useful to start the engine when its cold.
as tshih notes its hard to start. start it. let it get warm for 5 minutes.
clamp the hose.

4. use the idle screw on the t/b to see if he can establish a low idle.
get it down to 1000 or slightly less if he can.
see if it will do it.

i've been doing a bit of reading up on this as you do when its a fault like this to see if owners of other early L jet systems installed in other cars have had this problem.

turns out its a problem in 928s.
Alfa Romeos. and BWMs.
but its not entirely clear, as is often the case, how its been solved.

i also haven't asked mike yet. and i will. he might have an insight.
wasn't much point until some diagnosis had been done.
which at least a little bit has been done now.

Posted by: tshih914 Mar 4 2023, 01:15 PM

While I am trying to sort this issue out I am also in the process of rebuilding a 1975 2.0L engine with D-Jet to upgrade my 1.8L currently in my 1974 914. I am at the stage of doing the valve train and was looking for my engine tins #4 and 5. I found also the decel valve still attached to the end piece engine tin. So can that decel valve be used to replace the bad one in the 1.8L

Posted by: wonkipop Mar 4 2023, 01:27 PM

i think its safe to say your fuel pump has been wired to run off the ignition as a result of its modification to location at front of car.

the afm plug out test we got you to do indicated that.

if your fuel pump was wired to run off the afm it would maybe have started and run for about 10 seconds at most. and after that it would not have started.

yours did start and duplicated the behaviour of starbear and van's car.
both of them had the f p wired off the ignition circuit and f p ran all the time.

it will be a little hard to do the AFM test the workshop manual way if the fuel pump is already running. AFM flap won't make a difference. i hope that makes sense.

a better test for you to do is turn the ignition on but don't crank and see if you can hear f p running.

do the test anyway. see if with ignition on and pushing flap does anything.
like switching the fuel pump off? i mean who knows.

with those high idle revs you were getting as a result of the AAV and the decel valve,
and assuming the boot was ok between the throttle body and the AFM the flap would have already been being pulled well past its idle position. both those devices feed into the section of air intake above the throttle body which is closed at idle. so the only place they can obtain air is from the AFM intake. (or a leak in the boot).

onward. one item at a time.

EDIT
actually do the flapper test.
just to make sure the flapper is moving freely through its full arc and is not binding or catching anywhere. worth doing just for that check.

Posted by: wonkipop Mar 4 2023, 01:31 PM

yes.
its the same decel valve in the 74 L jet.

may need adjustment though.

you can try it.
but for now i would just take the decel out of the equation and leave it out while we stay on the hunt.

i don't think your problem is a decel valve if you know what i mean.
thats not going to solve the issues.

whats going on with your car are several distinct problems over the top of each other.

we got rid of one of them. a faulty decel.

eventually when everything is sorted you can put a properly adjusted decel back on.
to me its the last item you would reinstall back on at the end of this.

as i have said. i don't even have one on mine and haven't for all the time i have owned and driven it. 34 years.

EDIT
the decel valve will not be attached to engine tin.
its in all cases mounted off the inner engine bay bodywork on rhs of car.
whats mounted off the engine tin is the fuel pressure regulator.
thats probably what you are looking at.
looks very similar to a decel valve.
esp the f p regulator on a D jet. it has an adjusting nut on it i believe that can make you think its a decel. the f p regulator on the L jet has no adjustment nut but is mounted on same place off engine tin on lhs like a d jet. its just a mounting nut on a L Jet.

Posted by: wonkipop Mar 4 2023, 01:42 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

where i would want you to go next is the throttle body and throttle body switch.

you have a new intake boot and a t/b gasket.
so to install those the t/b needs to come off anyway.

you can give it a good clean.
check the idle passage is clear.
and take the t/b switch off.
see how clean or dirty that is.
test it as per workshop manual.

lets make sure that is all tip top and working right.

Posted by: Geezer914 Mar 4 2023, 01:45 PM

The AFM could be bad. Send it to Fuel Injection Corp in CA to get it checked out.

Posted by: wonkipop Mar 4 2023, 01:52 PM

he has a brand spanking AFM from fuel injection corp.
so unlikely its that.

but i would not discount it as a dud rebuild.
but doubtful.

Posted by: wonkipop Mar 4 2023, 01:55 PM

if this is what you are talking about @http://www.914world.com/bbs2/index.php?showuser=4426 then its a fuel pressure regulator for a D jet not a decel.

Posted by: wonkipop Mar 4 2023, 02:31 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

i had done some snooping about with google searches.
(anything about L jet problems, including your car, interests me for purely selfish reasons )
i was going to ask my mechanic mike about this too.

read this article.
its specifically about Alfa Romeos fitted with L-Jet.
but it does not matter.
the systems are very similar across cars early L jet was fitted to.
go to section about electrical grounds.
i think he calls it step 2 in this article.
he specifically mentions the "starts and stalls syndrome".
not sure that is the problem you have, but perhaps it is.
others on 928 forums also refer to the "starts and stall syndrom" and lack of power when accelerating problem. which this kind of is. esp if we can get the high idle behaviour out of the picture and stop it masking what will be the pure behaviour of lack of throttle response/dies problem.

https://hpsimotorsports.com/blogs/tech-articles/gregs-bosch-l-jetronic-fuel-injection-idle-adjustment-diagnostic-and-tune-up-page

i did notice in one of your earlier posts that the ECU in your car seems no longer to be bolted to the factory fixing off the battery tray and is instead floating about in the corner of the engine bay above the hell hole region. and its plug is oriented upwards which i don't think is ideal in terms of moisture entry. not sure how long its been that way in your car or whether you have it temporarily in that state while you have been doing this work.

i'd want to check that connection plug to the ECU.

have a read of the article for some guidance.

Posted by: nihil44 Mar 5 2023, 12:29 AM

I have removed and replaced the AFM many times for various reasons - 3 operations. Undo hose clamp onto the intake boot, undo clips on air filter, disconnect AFM connector. On numerous occasions on starting the car up again I have found the car would start but dies when the throttle opens - WTF I have forgotten to replace the AFM connector again.

Your symptoms seem to be similar. This test could be worthwhile. I may be barking up the wrong tree but indulge me for a moment.

Will the car start and run with the AFM unplugged? If not, don't bother with reading further.
If so, how about starting the car and running the car with AFM connector unplugged and adding the gas and see if the motor dies. This may disclose that the problem is in the AFM to harness interface ie connector interface

If it dies, then start the car with AFM plug connected and (2 persons required) have one person open the throttle while the other jiggles the AFM connector plug and the AFM connector wires . The purpose is to possibly reveal a broken wire in the harness making intermittent connection or poor contact or corrosion in one or several of the 6 pins in the connection

Simple test and I may be way off the mark but worth a go. I feel yuor pain!

Posted by: wonkipop Mar 5 2023, 02:08 AM

@http://www.914world.com/bbs2/index.php?showuser=14058

yep it could be the afm connector.

but what you need to realise @http://www.914world.com/bbs2/index.php?showuser=14058 is that you don't have a legit factory connection to how the fuel pump works either.
(and neither does our friend).
and we have done your test./or our test, the same thing.
read back a page or two.
the car should not run period with the afm disconnected if its legit original.
most it should do is run off the cold start injector for about 10 seconds and then quit.

but
"i'll fix vapor lock" etc.....and we are now in that!


so many of you don't have a legit system you can benchmark against the factory manual
50 years of "bogan" departures from the system.
the thing about it starting and then dying when you go the gas is not legit system,
or it is?, but you have to read it carefully.
its because you have a fuel pump which is not operating off the afm flap that the car runs at all.
if your fuel pump ran off the afm flap in the first place it would not run at all to even be in the space we are in.
see above.
but........that doesn't mean you are not close to the truth.


i think the problem connection could be in either of the plugs.
either the plug to the afm or the plug to the ECM.
or an earth problem.
or as you say the harness.
but thats not the reason yours quits when you gas it with the afm plug out.
because it should not even go with the afm plug out.
if that makes sense. yours quits whether the harness is good or not. or the connections and plugs. if the afm plug is out. because its artificially going in the first place like our friends. its being run when it shouldn't even run. in a stock L jet the afm runs the fuel pump. period. end of story. so to be accurate what is going on here is that something is not going right when the throttle body switch signs off on "i am finished with telling the ECU i am done with the idle circuit --- its all over to you and the AFM to tell the engine what to do". which is why you are right about the harness. or the plugs? maybe.
because there is still the distrbutor? one thing at a time?!

i must have one of the last fully intact L jet systems left.
i've never shifted the fuel pump.
the only thing out is the decel.
the rest of its factory intact.

so mostly i can do the trouble shoot and i am not getting misinformation from unaccountated for "improvements".

Posted by: wonkipop Mar 5 2023, 03:03 AM

i think what i am trying to say @http://www.914world.com/bbs2/index.php?showuser=14058
is this.

we are on about the same thing.

if it was a legit factory L jet set up it would not even idle.
so lets leave that out of it.

its idleing. sort of. because its getting fuel. illegitmately.

and because it has a non legit L jet fuel pump power scenario it will idle.

-----
but as soon as you crack open the throttle it all goes to hell.
because thats when the ECU wants something more than the whatever the signal is from from the t/b and t.b position switch to idle.

and its not getting it?
because the plugs are dirty, the harness is farked or its not earthed reliably.

amongst other problems
because seriously. its all farked. the decel is farked up. the AAV is maybe farked up.
and why wouldnt they be. its 50 years old. you have to give it a break!
and help it.

Posted by: wonkipop Mar 5 2023, 03:37 AM

further thought @http://www.914world.com/bbs2/index.php?showuser=14058 and @http://www.914world.com/bbs2/index.php?showuser=26011

i reckon if this baby was OEM wired up it wouldn't even run the fuel pump and idle to even get to the point where it was stumbling when you opened the throttle.

so..........the hot rod set ups of fuel pump actually provides an insight?

i'm thinking back to his plug in/plug out afm test,
it did something.
but regardless the engine would run at idle?
and we know no way, unless either fuel pump gives fuel.
either provided by wiring.
or by AFM flap.
thats the only two scenarios it can run at idle and get fuel.

but once she goes on to throttle off idle stop it has to be AFM.
or its all over?
the fuel pump can be delivering fuel.
but the ECU expects information about how much air is coming in, air fuel ratio sincro etc.

Posted by: Geezer914 Mar 5 2023, 06:00 AM

Go to Bowlsby's web site and print his wire diagrams for Ljet. Get a test light and do a continuity check of the wire harness from the ECU plug. I had a bunch of cracked wires that I had to replace.

Posted by: Van B Mar 5 2023, 10:33 AM

Wonkipop. I agree that the TPS may be an issue or even the ECU, but he’s got to solve the obvious issues first… control the variables. In general, people’s approach trouble shooting cars loke theres an OBDII port and a code to read. But we’re talking about an open loop vacuum system. And computers that are little more than if/then statements as code.

-Fix all potential vacuum leaks
-confirm baseline settings
-confirm fuel, air, spark per cylinder
-confirm timing (difficult to do at this point without a stable idle)

We’re doing a whole lot of talking in thinking without much information at this point. You already said it, @http://www.914world.com/bbs2/index.php?showuser=4426 has got to get methodical. Four pages into this thread and the airbox lid just now being removed is a SMH moment for sure.

Posted by: tshih914 Mar 5 2023, 10:12 PM

Took the throttle body off to inspect and clean the mating surfaces and replaced the seal. The pin hole is clear of any obstruction and was attempting to check the plug harness for continuity at pins 2, 18, 2 to ECU. However the 2 10 mm bolts at the ends of the harness just spins freely without the bolt backing off. I suppose I have to cut the heads off inorder to get access to the pins at the ECU end of the harness.

Posted by: wonkipop Mar 5 2023, 11:34 PM

nuts do not release harness plug.

this is how you do it.
press down on the little spring clip.
this will release the bottom of the plug.
pull + swing it out from there, it will pivot on its upper hook connection.
once swung out far enough pull downwards off the hook.




all this is described in factory workshop manual.
have you downloaded it from the links i gave you back on page 1?
it will tell you how to do all these things without breaking anything.


the nuts hold the ECU into its support sleeve.
which should be fixed on to the edge of battery tray.
this does not seem to be the case with yours?
the ECU is just laying around in there?
the nuts have probably stripped the thread in the support sleeve.
the sleeve is made of plastic and is delicate.
EDIT, its been a while since i had my ECU out to clean around in that area.
i got the ECU out of that sleeve and i seem to remember those bolts are captured.
once you undo them a certain amount the ECU just slides out of sleeve.
i could be wrong, its been a while. but irrelevant to releasing the plug connector.

you missed inspecting the throttle position switch. TPS.
and testing it?
its connected to the underside of the throttle body.
checking whether you hear click of switch when you open t/b from closed.
but we can return to that.

Posted by: wonkipop Mar 5 2023, 11:39 PM

take a photo of the ECU pins and harness plug when you have them apart and post it.

be delicate with it all. it looks like it might not have been off for a long time maybe.
so just go easy at it.

Posted by: wonkipop Mar 6 2023, 03:30 PM

yes to all.

thats why i was keen for him to see if he could at least bring the idle down a little with the idle screw and the errant AAV and decel out of the picture and isolated.
its important to know if he can affect the idle with the screw at all and start to get something like a lower steady idle close or closer to normal.
or is the whole thing still being overwhelmed by another air leak that has not been found.

------

i think the TPS needs close inspection.
electrical test to see if its working.
and the mechanical test to listen for the audible click from the switch as the throttle is closed.
there is the ability to adjust its position with the fixing screws.
so that it can be put back in spec mechanically if its ok inside electrically.

they are vulnerable to filling with gunk as the car ages.
similar to the wear bushing problem of the throttle body itself.
the o-ring seal goes between t/b and TPS. lets condensed crankcase vapors etc gradually build up inside it if it can get in there.
its one of the faults of choosing a vertically alligned throttle plate pivot.
a lot of other manufacturers used a horizontally alligned throttle pivot with TPS off to one side rather than at bottom. a slightly friendlier position.

TPS must be fully ticked off.
its not a hard test to do.
you have to be able to trust each of these things by checking them one at a time.

we have to be sure the ECU knows when the throttle is closed so it can operate correctly on its idle circuit (or mode whatever you want to call it in one of these old analogue devices). .........as part of getting to a basic timing setting/adjustment.
we also need to know if the switch is doing its job to let the ECU know the throttle has opened. then we can trust it and move on.

Posted by: tshih914 Mar 7 2023, 08:39 PM

Thanks wonkipop for saving my bacon and not butchering the ECU mount. I have followed your instructions and got the cable opened up without damaging it. I have also learned how to post a video on my Youtube channel https://www.youtube.com/shorts/HT8ScUYyYdw showing the throttle switch making the clicking sound for what its worth. Next I will use a ohm meter to check continuity of cable pin #3, 18, and 2 from throttle valve cable to ECU harness pin(which number pin corresponds to those connected to the valve?)

Posted by: tshih914 Mar 7 2023, 09:03 PM

I went to the manual and checked the wiring diagram which shows wires # 9, 20, and 17 which I think corresponds to pin # 3, 18, and 2 . Would someone provide the key for the pin position at the attachment point to the ECU for me to identify pins 9, 20 and 17.

Posted by: wonkipop Mar 7 2023, 11:24 PM

thats great about the tps making the clicking sound.
it should do it just as you crack open the throttle and just as its closing.
sounds like its ok.
you can do an electrical test on it too.
to confirm it all.
but it sounds like you can tick that off.

i'll have a look later and see if i can find the pin diagram for the ECU and post it.
with a bit of luck someone else might post it for you before i get hold of it.

Posted by: bob164 Mar 8 2023, 01:56 AM

Jeff Bowlsby's excellent website has a "914 Tech Notebook " section.

https://bowlsby.net/914/Classic/TechNotebook.htm

The ECU Connector pin-out is on page 22 of the "Technical Manual L-Jetronic Fuel Injection System".

Hope this helps,
Bob

Posted by: wonkipop Mar 8 2023, 03:52 AM

ah good.
@http://www.914world.com/bbs2/index.php?showuser=21877 has given you the links.

in case you can't stumble on it.

here







BTW i always had the battery disconnected when i pulled that ECU plug.

Posted by: wonkipop Mar 8 2023, 04:45 AM

by the way i think i have had a thought about how this thing is actually running.
@http://www.914world.com/bbs2/index.php?showuser=26011 can offer his criticism on my ridiculous idea?
or any one else for that matter.

i don't think its starting and going to "idle" with the usual assistance of say the cold start injector etc. ie a normal start to a fast warm up idle. hence the hard starting.

nor do i think the original description of high idle at 3000 rpm is correct.
thats not an idle. thats what we used to call an engine that was "racing".
its half way to red line!!!

i think this thing might actually have been permanently in the twilight zone of thinking it was deaccelerating. with enough cranking, it sprayed enough juice in there to finally fire.
and once it fired with all the air it was getting from the faulty deacceleration valve and AVV it went straight to stuck wide open decel valve mode. 3000 rpm and stayed there.
because it can? there is no fuel cut off at throttle close off from high revs in an L jet except via the AFM flap. and if fuel cut off does happen it only happens if the afm flap descends past the point where the contacts are to activate the f/p. (why the decel is there in an L jet in the first place, to stop that). i put a proviso on that of course, it will only cut off the fuel if the fuel pump is properly wired to AFM control as it is stock.

i'll think more about this.

but in summary so far.

car:

1) starts with difficulty. (something is amiss in the cold start set up).

2) when it starts runs in jammed decel mode with tps indicating idle position and communicating closed throttle but AFM flap at elevated point on arc of contacts.
(which is a perfectly legit situation for L jet - although usually only momentary ).
its kind of a zombie?

beyond that i can't think whats going on when you try to gas it.

everything has to be properly set to really test transition to opening throttle.
valves adjusted.
points. timing (including dist advance function checked).

we know its got legit fuel pressure.

anyway its just a thought at this stage and further testing of components has to be done.

the cold start injector and the thermo time switch that controls it need checking in relation to hard starting.

Posted by: tshih914 Mar 8 2023, 05:53 PM

I tried to check the wires from the throttle valve switch pins 3,18,and 2 for continuity at the 2 ends (ECU and valve) as shown in the 3 photos. Meter set for audible beep and there was no sound. Am I doing the test correctly?

photo below testing pin #2 to #2 on ECU end


Attached thumbnail(s)

Posted by: tshih914 Mar 8 2023, 05:54 PM

Between pins #3


Attached thumbnail(s)

Posted by: tshih914 Mar 8 2023, 05:58 PM

testing pins #18


Attached thumbnail(s)

Posted by: wonkipop Mar 8 2023, 07:17 PM

you operate the throttle while doing the test.
and thats

1) testing the switch itself.

and then

2)
if you want to test the connection to the ECU you need that plugged back in and test it at the ECU plug pins.

is that what you are doing?


--------

Posted by: wonkipop Mar 8 2023, 07:46 PM

@http://www.914world.com/bbs2/index.php?showuser=26011

i spoke to mike this morning.
as i thought the AFM will run the engine according to where the flap is and the ECU will provide the fuel, no matter the throttle switch saying its in idle.
it accepts the inputs. despite the real throttle being closed and the psuedo throttles open (the decel and aav). both of these are acting as "metered air".

he doesn't think that is why it stumbles when you open the throttle.

Posted by: tshih914 Mar 8 2023, 08:38 PM

[quote name='wonkipop' date='Mar 8 2023, 05:17 PM' post='3063545']


you operate the throttle while doing the test.
and thats

1) testing the switch itself.

and then

2)
if you want to test the connection to the ECU you need that plugged back in and test it at the ECU plug pins.

is that what you are doing?

Initially , no. When I did as you described the throttle switch test pass when the throttle was opened sufficiently for there to be continuity between pins 18 and 3.

2) when plugged in there was continuity between pins 2 or 3 with 18when throttle is fully closed.

Posted by: wonkipop Mar 8 2023, 08:55 PM

here is a y t vid i came across a few years back on t p s for L jet.
he opens one up so you can see how it all works.
including the type that is on the 914.

https://www.youtube.com/watch?v=WHoeE81ZcHU

Posted by: Van B Mar 8 2023, 09:19 PM

Our TPS really only tells the ECU to send fuel for idle, neutral for driving range, and then enrichment for wide open.

Posted by: tshih914 Mar 9 2023, 06:40 PM

The inside of my TBS is reasonably clean and it passed the test of throttle opening resulting in 0 ohms resistance when throttle is opened. So the racing/idling at 3000 rpm with throttle fully closed is indication of what's not working correctly?

What component should we test next?

Posted by: wonkipop Mar 9 2023, 07:57 PM

CHT

cylinder head temp sensor.


after that pull the AAV off. Aux Air Valve.
clean it out. carb cleaner is good. get it thoroughly cleaned out.
probably full of gunk.
put it in the freezer/cold fridge for half an hour after you have cleaned it.
see if its (EDIT) open. you look down the bore and hold it up to the light.
if it is (EDIT) open hook it up to a 12V source. like a car battery for instance.
after 5 minutes or so on the current it should be closed. or very nearly closed.
hold it up to the light again and inspect to see if thats the case.

basically you should be testing everything on the EFI.
everything.

then the ignition. in particular the distributor.

you need to be sure everything is working.

while you wait to get your hoses and seals.

the ECU is the hard one to really know.
you still have not answered my question.
how long has it been lying around loose in the engine bay.
the plastic sleeve you almost went hammer and tongs at provides it with an isolated mounting so its never lying on anything hot or subject to random electrical shocks etc.
?


we have already explained to you why it was racing at 3000 rpm.
its pulling air through the decel valve and the AAV.
this is metered air, not air leaks. ie those malfunctioning components were pulling the afm flap open just the same as if you had the throttle opened.
you (or someone before you?) had screwed the throttle idle screw right down hard closed to try and calm it down. your car has never been idling in that state.
its been racing with a psuedo throttle open.
the timing is probably out. etc.

what we don't know is why it stumbles when you open the throttle.
although there was a clue when you did one of the tests i suggested to close off the decel and AAV hoses and you reported it almost did not stumble over when you opened the throttle. unless i misread your report.
this might offer you some hope.
i could guess the stumbling might be in part antagonised by some further genuine air leaks in the system. ie air which is not pulling the flap open in the AFM but causing the mixture to lean out. but i am really not sure. its impossible to know until the entire system is verified. vacuum hoses, seals and all. its always been my experience that unmetered air leaks do not cause the engine to race, rather they cause it to be unstable and unsteady at idle and often mean it just dies and won't run.

the point you need to get to is a proper idle and a proper cold start.
by proper idle i mean an idle set off the t/b idle screw and with the ignition timing verified and properly set. thats step 1.
and you won't get there until you go right through the system.
by the end of it you will know every bit and what it does.

Posted by: Van B Mar 9 2023, 09:12 PM

Wonkipop, you meant open on the AAV when you put it in the freezer. Then closed when it warms up. Even if the heating element is bad, this AAV is still good about closing when the engine warms it up. But the spring does get tired and won’t open all the way anymore… unless it’s gummed up.

Otherwise, based on the neglect while sitting for years. I guarantee the injectors aren’t working either. Bad spray pattern or too clogged to increase flow are very probable issues.

But what I said in post #120 is still my opinion.

Posted by: wonkipop Mar 9 2023, 09:31 PM

ah sh$t.

sorry. i meant that. dyslexic today.

i agree with post #120.
and more.

Posted by: tshih914 Mar 10 2023, 08:54 PM

@http://www.914world.com/bbs2/index.php?showuser=24231

The ECU was not left dangling loose in the engine bay. It was securely mounted to the rubber mat on the firewall by a long screw into the firewall so I believe it is not damaged.

I did notice the CHT was very rusty and probably needs to be replaced. I think it is a thermocouple resistor that register about 300 ohms when cold and resistance goes down when hot. Checking it is just a matter of measuring the resistance at the two ends (head of the part that screws into the cylinder head and tail of the wire leading to the ECU harness)

I have received the hose kit and am in the process of removing the AAR and cold start valves for testing and cleaning. That hose kit does not seem to have the right number of hoses or some of which are too short to replaced those currently in my car.

Posted by: wonkipop Mar 10 2023, 10:05 PM

ok thats good about the ECU.
makes me look less sceptically at it in photos.

sounds like you got a bit of momentum up now.
good luck with testing and checking all the bits.

did the hose kit come with a guide drawing for each hose?
would be unlike AA to have that wrong i think.
list up anything specific you encounter with a photo and perhaps we can check it against what should be there and where they go.
you will find my hand drawn hose diagram is accurate, its off an original cond car.

Posted by: wonkipop Mar 11 2023, 01:56 AM

@http://www.914world.com/bbs2/index.php?showuser=4426

you might wonder why i am touchy about ECU's

a little story.

got a friend of sorts who owns a late 90s BMW M3.
who has had a saga that has lasted 5 years.
for some reason two decades ago he bought one of the so called "clutchless"manuals.
early tech.
not a paddle shifter on steering wheel but you flick the gear lever version.

anyway.

it started sh#tting itself after you shifted gear.
went into 3 cylinder limp mode.
for a while he got away with switching it off and restarting.
but it just got worse.

when the BMW "i am a cripple" business started, our resident mechanic mike,
said - "its the ECU".

the owner grinned and decided not to take the advice.

5 years later, having done everything, and having taken advice from every dickhead under the sun, at the BMW club, the alfa romeo club etc and so forth, having replaced oxygen sensors, rebuilt the vario cam unit whatever its called on a BMW, etc etc etc etc - having searched every BMW forum on the globe to get opinions, he finally found another BMW "REAL expert" from the era who was retired. guy said the same thing as mike.

"ECU mate"

and then he contacted BMW to get one.

they said. "lucky fer you mate, ve haff vone left".
one in the entire world.
(because its a special ECU for the dumb arse flick shift clutchless manual).
rare as hens teeth because no one else was stoopid enough to buy them.
most sane punters bought the three pedal fully analogue version.
its better.
but don't say that to my "friend".

anway - so he got it. all special delivery from germany.

and some tech experts here at a special BMW workshop hitched it up to his engine and did some keyboard work etc and.......it goes.

but thats it. he is farked if it happens again. there are no more ECUs for that pile of bavarian excrement. (please excuse my negative opinion of german gum tree magnets).

---

in short what the original ECU was doing was cutting to 3 cylinders to accomplish the shift, because thats how high tech its low tech was. but then it could not reconnect to all 6 cylinders after the shift. so it was stuck in the zombie world of half way through a gear shift.

----
now a 914 ECU was built to survive on the surface of the moon. its seriously over-engineered. military grade. but its half a century old. i'm sure bosch would be both astonished and smug at the same time that these things are still going.
but you know the older they get the less tempted we should be to subject it to conditions equal to a straffing pass on an afghanistan mountain hide out for el quada or a bomb drop on bagdad.

Posted by: StarBear Mar 11 2023, 07:41 AM

Posted by: Van B Mar 11 2023, 08:29 AM

The ECU is very obviously not mounted to a rubber mat, on a firewall, with long screws.

Posted by: tshih914 Mar 11 2023, 01:03 PM

I went to check the CHT sensor (which is really difficult to get to buried under engine tin near spark plug #3) Just measured the resistance from the connector rectangular plastic piece to engine ground and it read 1.77kohm. I don't know what that means as I expected around 300 ohms cold. Will check once the new part comes in from Amazon.

The next thing I did was to remove the AAR and sure enough the valve is open when cold. However when I connected 12V to the 2 pins at the connector after 13-20 min the valve felt warm to the touch but the opening did not close so that valve is broken.

Also in looking at the valve there appears to be a post for grounding wire/connector? that was not attached to anything.


Attached thumbnail(s)

Posted by: tshih914 Mar 11 2023, 01:59 PM

Posted by: StarBear Mar 11 2023, 02:23 PM

Might want to squirt a few drops of silicone spray in there just in case that loosens things up a bit. Worked on mine which was mostly working but needed a little encouragement to behave.

Posted by: tshih914 Mar 11 2023, 02:42 PM

[quote name='tshih914' date='Mar 11 2023, 11:59 AM' post='3064228']
[quote name='tshih914' post='3064219' date='Mar 11 2023, 11:03 AM']
[quote name='Van B' post='3064146' date='Mar 11 2023, 06:29 AM']
The ECU is very obviously not mounted to a rubber mat, on a firewall, with long screws.
[/quote]

The photo was taken after I had removed the ECU to check the TPS and wiring and have discarded the rubber mat.

The fact that in one of the test where I pinched off the hose from the AAV to the AFM caused the RPM to drop from 3000 to around 1500 suggested that the AAV had been stuck open even after the engine had warmed up. I looked on Ebay and found a used AAV (for 75-79 VW bbeetle) with same Bosch part # 0280140101 for $80. Should I get it?

Posted by: wonkipop Mar 11 2023, 05:41 PM

ok @http://www.914world.com/bbs2/index.php?showuser=4426 .

thats good affirmation re the AAV.
combine that with your errant decel valve and you probably pretty much have the source of uncontrolled metered air that were likely significant contributors for the elevated "idle".

as @http://www.914world.com/bbs2/index.php?showuser=10753 suggests you could see if you could coax the AAV to life.
the AAVs are hard to find these days.
if you cannot bring it back to life there are ways to deal with it.
it is useful for cold start.
and some members like @http://www.914world.com/bbs2/index.php?showuser=25740 have rigged manual taps in to the hose to the air inlet tube so they can switch it out of the air feed circuit after its done its job for 5 minutes at start up,
you may have to rig something like that up so that you can use it for the cold start and then once the engine is warm take it out of play. you want it to be able to be closed once you get to the point of tackling a stable warm engine idle.



as to the one on ebay.
i would communicate with the seller and ask if he can reassure it actually works.
maybe some photos that document a test of it open and closed or something.
you don't want to lay out $80.00 on just another screwed AAV.
they are all old and tired at this point in time unless somehow one thats been in a box sealed in plastic for 50 years.

Posted by: StarBear Mar 11 2023, 06:08 PM

AAV FS in classified FS/WTB forum, as Van B highlighted. $65. Unsure if working?

Posted by: wonkipop Mar 11 2023, 06:30 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

you mean this arrowed.
its just an engine tin screw and washer.



the technique for how to get the CHT out is in the factory manual.
it could be tricky if its never been out like all things are that are in threads and have never been undone for half a century.

mine worked so luckily i did not have to remove it.
i think @http://www.914world.com/bbs2/index.php?showuser=26011 did take his out and replace it.
he might have some tips if you are lucky.

Posted by: Van B Mar 11 2023, 07:27 PM

Fixing the AAV is not going to make the car take throttle. And a full open AAV will not make the car idle at 3k. I bought one for a BMW that is slightly bigger than stock and it gives me a healthy 1500rpm cold start idle.

Further the heating element cannot completely close the AAV. It still needs engine temp to get hot enough to close. The heating element provides a good head start so you don’t have 10min of full high idle.

With age and heat cycles, the spring gets lazy and the part neither opens or closes fully. They also get carbon deposits over the years that can gum them up at the disc.

Posted by: Van B Mar 11 2023, 07:39 PM

Likewise, the CHT will not cause the car to die when you touch the throttle. But to remove it, coil the wire around the screw driver so you can fit it inside a deep socket, slide the socket over until seated, then attach the ratchet. Conversely, you can cut a slot in a socket like an O2 sensor socket.


Attached thumbnail(s)

Posted by: wonkipop Mar 11 2023, 08:58 PM

i believe it was the combo of AAV and decel that was giving the full 3000?

once he clamped off decel it did drop significantly.
and similarly when he clamped of AAV.
not sure he did them both together.

also clamping still lets some air through the hoses.
to really take them out the test has to be done with hoses out and plugs in.

also you can get excessive air leaking past the throttle plate around its edges if its not adjusted properly on its stop. will also pull the flap on the AFM.
that can contribute a portion of the high idle. but i wasn't going to go there just yet.

i agree not taking the throttle is not likely about these things.
a further matter that is aside from these things.
even mike was not sure about that, saying, well......it could be lots of things.
then repeated the mantra. valves have to be adjusted. timing set.... etc.

that is true about the electric current not doing it completely for the AAV.
i noticed that about mine when i tested it a few years back.
it did shut but not completely.
i showed it to mike at the time and he said, yep thats ok. said no more.
but it certainly shut to a significant degree.
if this ones not moving under electric current at all it would tend to say it needs some attention and love to see if it can be raised from the dead.

Posted by: wonkipop Mar 11 2023, 09:15 PM

these are the test values for the CHT.
again from the factory manual.
its in there you just have to look for it.
it can be a bit all over the place finding the stuff as some information gets mixed around with the D jet stuff.



yours might be alright? if you got 1.7 k ohm.
i guess it depends on how cold it is there currently where you live.
at 68 F it says you should get 2.5 K ohm.
and progressively less for colder temps.

Posted by: technicalninja Mar 11 2023, 09:40 PM

Think you have it backwards...
With NTC thermistors resistance decreases as temperature increases.

I will slope a NTC sensor. Put it in freezer, record resistance, refrigerator, record, room temp, record, hot tap water, record, boiling water, record.

I want the slope between each point to be similar for all...

Sometimes you will find a sensor drops out at a certain temperature.

Posted by: wonkipop Mar 11 2023, 10:10 PM

@http://www.914world.com/bbs2/index.php?showuser=26011

this is his report that interested me.

it was clear from the photo that the AAV was still connected.
idle screw as out two full turns as you had suggested.

revs were now down at 2,500 from 3,000.
not attempted to do the further steps we suggested.
1) block off the AAV after the engine had warmed.
2) adjust the idle screw to see if he could lower idle revs.



it seemed to me the engine was able to act a little in that narrow 500 rpm range.
it depends how gentle he was opening the throttle.

can you see where i am going?

what i want him to do is get the engine to idle revs i he possibly can.
or a steady lower idle.
if he can what i would want to do is gently manipulate the throttle.
very gently.
see if it will rev to 2000.
if it does.
see if it will rev up to 3000. (we know it can run there and off the AFM flap too).
if does.
gently take it over 3000.
see what it does.
each step taken gently, not just stabbing of the gas pedal.

i'm going to dig up some diagrams i thought i had on the AFM and connections from potentiometer to plug.

so far all his electro vac / sensor components are checking out.
assuming valve adjustment and setting of timing (which can be done at idle) he should be able to get this thing to idle at lower revs with if the decel is kept out of it and the AAV is closed when its warm.

it may not be what i am thinking of.
in which case? have to think again!

Posted by: wonkipop Mar 11 2023, 10:12 PM

yeah you are right.
i'm backwards on that.
another naturally dyslexic moment.

Posted by: tshih914 Mar 11 2023, 10:17 PM

I posted a bunch of videos and shorts on my YouTube channel @http://www.914world.com/bbs2/index.php?showuser=3734 .
link here: https://studio.youtube.com/channel/UCmLvtTxokU7diByRQaSm46Q

Posted by: Van B Mar 11 2023, 10:41 PM

I’m sorry, but it seems like everyone is forgetting this car was unceremoniously parked for years. I know without a doubt the injectors are in bad shape.

Remember, I bought 7 NOS Bosch injectors and had them all dynamically tested, 2 failed for spray bad spray pattern and 1 for low flow in part throttle conditions. So, if a new injector in a box can go bad, why not one that was just parked full of fuel?

This racing idle is a red herring IMO.

Posted by: Van B Mar 11 2023, 11:06 PM

After watching the video of the car running, it’s entirely possible that the AFM is incorrectly calibrated. Spring could have too little tension and is allowing the flapper to open too much at idle. But also, the injectors could be dumping fuel and you’re just choking it down by clamping the AAV.

Regardless, you have yet to confirm the timing, or assess the plugs after running the engine.

Posted by: wonkipop Mar 11 2023, 11:53 PM

well, it is and it isnt. a herring of the red variety.

its certainly one of his problems.
and should be eliminated.
unless he likes just sitting around in it with it yelling at 3000 rpms stationary!

eliminated - before he gets to the real one.
which is why won't it take throttle.

which may well be what you suggest.
likely either fuel. or ignition.
and i'd start with fuel.
if it isn't then.........

been my experience that injectors are cactus completely after a long layoff.
and if not spraying properly would still accept some application of power?
not just die totally. but fuel pressure on throttle demand is in the same league.
i can see how that might happen if there is a troublesome kink in the fuel lines somewhere. recent work involved renewing them all? potential there?
that will drop your injectors out - no problem.
his fp is fine at idle but it has not been examined in other states.
was going to get to that.

---

what will become evident is once these large metered (at present uncontrolled) air routes are tamed any unmetered air leaks will make their presence felt as he tries to lower the idle. they will cause it to lean out. and if they are there they will need to be eliminated.
helps to be able to get the idle down to do the timing!!!!. kind of a catch 22.

then its the throttle problem. which you can start to trouble shoot properly.

just the way i do things.

might be worth investment in new injectors.
at least you can rustle some up for a reasonable price in the USA.
be good if thats all it was. but i am not sure i would jump to that just yet.
but i agree its probably on the cards.

so far it looks like most of his stuff works aside from AAV and decel.
maybe a question mark on CHT but its kind of OK.
enough for this exercise.


------

i can't seem to get his youtube link to work to listen to the engine.

interesting observation you make @http://www.914world.com/bbs2/index.php?showuser=26011

i think that is what i was beginning to think about before in prior post.
about seeing if it would carefully take throttle if idle revs could be brought down.
was it something to do with where the potentiometer was at on the AFM driven by the flapper and was this in the right place?

Posted by: technicalninja Mar 12 2023, 12:13 AM

just quickly looked through this thread.
I have UBER experience with the version of this fuel injection that Nissan used in the 75 and up Datsun Z cars.

I traded my first rat box 914 for my first Z car and its been nearly 40 years between 914s but I've ALWAYS had a 1st gen Z car. I have 10K lbs of stripped Z car parts...

Datsuns did not have decel valves. They used dash pots on the throttle linkage for the same reason.

Everyone has given good advice but it looks like there are "too many cooks" in the kitchen for me...

It also looks like the original poster is not experienced in fuel injection diagnosis and trying to help across keyboards can be difficult.

I'd base line the car first.
Pull plugs, inspect and do compression test. record numbers.
Check ignition stuff over; cap, rotor, wires, points if still in use.
I'd test both the vacuum advance/retard and the mechanical advance in the distributor.

what is the age of the fuel in the tank?
If it's over 1 year old completely drain tank and replace with fresh.
A new fuel filter should always be installed if a fuel poisoning has occurred.

Any gas with ethanol in it is complete trash after 1 year and suspect bad after 6 months.

Test fuel pressure with a gauge and a vacuum tester hook to regulator. Appling vacuum should decrease fuel pressure. Z numbers were 36 no vacuum and when vacuum is applied the regulator keeps a 36 psi difference between manifold vacuum level and the injector.
15" of vacuum equals a drop of 7.5 psi,
20" of vacuum equals a 10 psi drop and so on.
When an engine is running properly and has good manifold vacuum at idle you can see 24-26 psi on the gauge idling shoot up to 34-35 psi when you snap the throttle open suddenly.
I doubt the OP has a good stable vacuum signal to work with right now...
Make sure you can see 36 psi when running the pump without the engine running.

Compression, fuel quality and pressure, ignition all check out...

I do what R-Towle suggested and get rid of all of the vacuum except the main boot between AFM and T-body, the vacuum line to the fuel pressure regulator, and the vacuum line to the distributor advance side.

I'd test and adjust the TPS. I just tested the one off my 75 914. There are 3 pins on the TPS unit itself. The outer pins never have continuity and when the throttle is shut you will see continuity between the center pin and one of the outers. Open throttle it goes to infinity on the meter (no continuity) and above 80% travel (wide open) you will get continuity between the center pin and the other side. You adjust the closed throttle side only. You adjust it to just gain continuity when closed.
The Datsun TPS works exactly like the Porsche except the Datsun is adjustable via slotted mounting holes and the Porsche is not. You could slot the mounting holes if yours needed adjustment.

Biggest thing with the TPS... you should be able to disconnect it and the car should run ok without it in the system. The idle will be affected but it will not be high, it will hunt and tend to be lower.

Oh, continuity is tested on a meter. You can have a beep that will often happen when you reach 0 ohms but trusting the beep is shooting yourself in the foot.
Set your DVOM to resistance (ohms) and look at what it reads with the leads disconnected. This is infinity and often will read O.L (over limits).
Touch the leads together and you will get a very low numerical reading like 0.02 this is continuity. Most DVOMs have a zero button that will take that continuity reading to absolute zero for extremely low resistance checks (which you don't care about right now)
Now hold a lead in each hand, you will get a different reading usually in mega ohms "M". You just checked resistance across a piece of meat. Across a human you will never see infinity and you will never see continuity.

FI diagnosis is a step by step process and if you miss something early in the process you will drive yourself crazy.

I self-taught myself in 1982 with a basic theory book much like the one Woki posted.
It took a while before it all made sense and I can learn faster than anyone I know.

I'm in agreement with Van B who is spot on. I would want to be able to hold the throttle slightly open and acheive running at 1500+ rpm with proper responce to throttle inputs before I ever started working on an idle problem.

Even if the car will not idle. I would expect to be able to drive it around in a fairly normal manner before I started nit-picking anything.

The whole closing the entrance to the airfilter off should have killed the car bigtime.

My money is on big vacuum leak, bad fuel, poor injector patterns (the ethanol jacks with injectors bigtime!).

Hope this helps
I type too much
Rick

Posted by: wonkipop Mar 12 2023, 12:17 AM

@http://www.914world.com/bbs2/index.php?showuser=4426

yeah that link is making me sign into google or something?
really weird. won't just link straight through to you tube.

EDIT

ok i got in to the film. did a search of your channel name and got it.

very interesting.
i am going to send that link to mike, our mechanic.

Posted by: technicalninja Mar 12 2023, 12:31 AM

And wait, there's more...

I was fighting bad AAVs back when they were 10-15 years old. I can't imagine one making it to 40...

All the AAVs I messed with were Datsun Z stuff but it looks EXACTLY what we have on the 914 and works in the same way.

The bi-metallic strip which makes them close properly get old with age (15 years here) and doesn't work properly.
The Datsun ones could kinda be adjusted by loosening the pivot bolt and jacking with the internal shutter but that never worked very well or very long.
The best solution was to purchase a new one and they were expensive and hard to come by 25 years ago...

You could always just leave it out and plug its connection. Cold idle sucked and you would have to nurse the car to temp but it wasn't a deal killer, just an annoyance.

They DID NOT require engine temperature to close. The heating element (which is what the electronics are for) was powerful enough to close a frozen one in about 5 minutes.

Yep, I use my refrigerator/freezer for many different automotive uses.
I currently store my POR15 in the shop fridge as it extends the shelf life 300%

Posted by: Van B Mar 12 2023, 12:44 AM

Regarding the AAV heating element. Based on your experience, I’m betting the rebuilt units don’t have the same elements as the original. Probably cheap Chinese parts…

Posted by: wonkipop Mar 12 2023, 01:13 AM

@http://www.914world.com/bbs2/index.php?showuser=26011

i watched that film again a couple of times.
and i'm mindful of your injector views.

only my experience is they just jamb up.

its a long weekend down here (but i'm working regardless, my lot in life due to the stupidity of my choice of profession made at age 17 )
mike will be sitting back on a lounge chair by a river bank and if he has iphone reception will partake of the video in between catching fishes.

but here is a scenario.
and it involves injectors.

i know my 914 would purely run off the cold start injector.
this was a functioning cold start injector.
it ran for about 10 seconds. quite vigorously. while it ran.
this was our first attempt to start mine officially after 16 years.
after all the gizmos had been checked by me that i have asked our friend to check.

after it died each time after three goes mike pronounced the injectors "farked".
made the sign of the cross and instructed me to secure "new" ones from the promised land. which i duly did.

the original main 4 injectors were not running at all.
we pulled them and tested them. corroded shut.
this was despite 3 weeks earlier having got them cleaned and tested.
in three weeks they reverted to non operational, non recoverable from coma state.

but the cold start injector was working. correctly. and boy it could run the engine on its own. until it switched off. exactly as it was meant to do despite the passage of 50 years since it was born and despite being asleep for 16 years.

do we have a scenario here where this baby is running off a cold start injector that is malfunctioning and not closing off? just keeping on keeping on and squirting a vile unatomised stream into the intake plenum.

then when you gas it and the main injectors really do need to work - narthing.
because they are literally not working? leans out. all over.

then you close the throttle and it comes back to life on its dribbling cold start injector.

i don't know.

------

i'd pull those injectors.
all of them.
cold start too.
and just see what they are doing.
point them at a bucket and crank it.

and i'd check the plugs.
like you have been harping about.

it was pretty informative to watch that film he posted.

Posted by: technicalninja Mar 12 2023, 01:15 AM

I didn't know "rebuilt" were even available...
They weren't 25 years ago.

I got my current 914 with a brand new progressive 2 barrel installed by the PO incorrectly. The choke was still tight, and he had no power wire run to it...

I killed the tension and the engine magically ran better.

The entire FI came with the car in boxes. I think I have all of it but I'm hoping you guys can help me identify what's missing.

I'm going to test pulse patterns on the injectors just to make sure they still work at all and then send them off to an injector cleaner as I don't own one to the fancy back-flushing test sets.
I'm not even going to try and run them before a professional cleaning.

I got a NOS fuel pump from 914Sixer and this car has a newer FPR on it now.

I'm going to change the plastic lines BEFORE I'm ever going to push modern gas at pressure through them. They scare the hell out of me...

I held a 914 throttle body for the first time in my life tonight as I was checking how the TPS worked before my first novel above.

I may have a bad throttle body as it does not auto return to the closed position. It doesn't appear to have any spring tension on it at all. It looks like it would cause all kinds of high idle issues the way it is now.

Compared to a Datsun throttle body this thing SUCKS!
It's TINY and it doesn't have a throttle stop screw. The air bypass is crazy. The TPS is non-adjustable, and the mounting flange/gasket/rubber cup looks like a sealing problem in the making.
I am NOT IMPRESSED!
I may need one of the pups anyway and I'm going to start looking for a bus throttle body as I believe I've read that it's a bit bigger.

This thing looks like it should be on a 1000 cc engine, not a 1800...

Posted by: wonkipop Mar 12 2023, 01:18 AM

@http://www.914world.com/bbs2/index.php?showuser=27135

i'm digesting your comments.
experience on J fuel injection totally relevant.
nippon EFI was faithful J implementation of krautrock systems.

Posted by: wonkipop Mar 12 2023, 01:29 AM

@http://www.914world.com/bbs2/index.php?showuser=27135 - yeah i just read through your big post up above.
i can see why you call yourself a ninja now.

his big problem is he can't get it down to 1500+ to start playing with the throttle.

thats what i was angling at.

just to somehow get it down to there and then gently play with the throttle.

but it seems like he can't get it down to there.

he has got a massive air leak.
but there are two sorts.
metered.
unmetered.
and you do need to separate them.

most people just think of air leaks as air leaks.
but each of the two types produces the opposite effect.

when i say metered air leak, i mean a part of the system that goes via the same route as the throttle.

its real fun getting your head around L jet.
its actually far more logical than carbies.
and its so vintage german. like listening to kraftwerk play music on home built prototype electronic instruments. whats not to like.

PS
thanks for the tip on POR15 and the fridge.
i'll pass that on to mike.
he is always whinging about POR 15 going off. lids sealed with tape etc.
not sure i will want to drink the chilled water we also keep in the fridge in the workshop if he does.

Posted by: technicalninja Mar 12 2023, 01:37 AM

But wait, there's more...

I've found huge masses of fuel deposits in gas tanks that have gone bad.
I've got a parts donor 99 Miata right now that you cannot open the fuel cap without vomiting...
I'm not going to clean it, just throw it away with the car.

It's a real good idea to actually look down into a fuel tank that's been poisoned.
I found what looks like an underground cavern with stalactites and stalagmites growing from fuel "fungus" in the tank. this was in a fuel injected Fiat Spider (same L-Jetronic stuff as 914s and Z-cars) that had sat 3.5 years, and this was before ethanol...

A badly poisoned tank must be either cleaned out of replaced.
One of the members on this forum makes new replacements.
I'd contact him for a new tank.
I'd pay 3 times what a cleaning cost to go new over cleaned.
Last tank I had cleaned cost $150.00 years ago.
I wonder if you can still get tanks cleaned?
All the radiator shops have gone out of business...

Posted by: wonkipop Mar 12 2023, 01:46 AM

sh$t
the horror stories about fuel that you guys have.
whats going on with the petroleum situtation in the USA.
the home of texas tea.
so far here we are not experiencing those problems.
but we did have a right of centre government in coalition with the farmers party.
and those guys are sticklers about fuel quality.
tractors = fuel = food.
i'm not so sure about whats going to happen now.
the opposites are in power.
this is not a poltical statement for the admins.
merely an observation about govt. fuel standards regulation.
and fear of what might be ahead of me.

Posted by: technicalninja Mar 12 2023, 01:48 AM

Technicalninja is a pretentious name for someone to call himself.

I did not name me...

My shop buddies did in 1991 long before the internet was a thing.
I got my "handle" the old fashion way, voted on by my circle of friends...

WITHOUT MY CONSENT!

Being called "super-tech" or "Mr. Goodwrench" is an insult in the automotive world.

'Hey guys, here comes SuperTech, lets see what he can mess up today" displays the usual use of a pet name in the shop.

The story of my naming will be in another post but when I know something I'm usually pretty good at it...

Posted by: wonkipop Mar 12 2023, 02:07 AM

i'd call ninja a compliment.
down here it would be.

when i was a kid we used to get these J kiddies shows on aus tv.
one of them was about these spooky ninjas who could leap backwards and do stuff.
i spent my whole childhood along with my mates pretending to be one.
trying to walk backwards and chuck ninja spinning star daggers at each other.
thats one thing about australia where it was in advance of the USA.
we established cordial post war relations with Japan before anyone else in the pacific.
despite WW2 and all its horrors we had iron ore to sell.
and J needed it.
its a curious thing australia's relationship to Japan.
we did an exchange with J TV stations in the 60s.
they got skippy the bush kangaroo.
we got ninjas.
we came out on top in that deal.

Posted by: wonkipop Mar 12 2023, 02:22 AM

here you go mate. @http://www.914world.com/bbs2/index.php?showuser=27135

i found it.
you can find anything on youtube.

phantom agents. aussie kids were obsessed with this circa 1965.
we would wear plastic breakfast bowls on our heads trying to copy this stuff.

https://www.youtube.com/watch?v=t2_tMhgisd8

more conservative kids were into SHINTARO.
he was your typical historical samurai figure.
but no way was he a ninja.

phantom agents were the sh$t.
you need to get into the phantom agent mindset to crack L jet.
no use being an american/aussie trying to tune a carby!

shintaro. (not really my scene when i was 7 years old).

https://www.youtube.com/watch?v=-eVZHgBkMWI

back to krautrock fuel injection.
these diversions are important.
there is lots that can screw up in L Jet of a mechanical nature.
which @http://www.914world.com/bbs2/index.php?showuser=26011 reminds us of.

Posted by: Geezer914 Mar 12 2023, 05:55 AM

Not to be redundant, but did you do a smoke test and check the intake runner gaskets???

Posted by: tshih914 Mar 12 2023, 09:26 AM

My fuel is OK as I have been very mindful as a chemist and have used fuel preservatives like Marine Stabil and I've replaced the plastic lines with stainless steel ones and installed all new fuel hoses. It is very possible my injectors are not working will have to pull them and test.

As far as our future use of fossil fuels and fuel quality concerns, those farking A-holes in power around the world (especially in USA) have been bought and corrupted and compromised by China CCP to force everyone to join the cult of Climate change and Marxism.

The new breed of electric cars are soulless and boring would much rather play with our old toys.

I have posted a short video on my channel showing the current resting state of my AFM showing a slight gap at the door which I was closing using a flat blade screwdriver. Is that gap (2-3mm) supposed to be completely closed in a correctly adjusted AFM?

Posted by: wonkipop Mar 12 2023, 12:39 PM

dunno.
i have not been poking around in my AFM for at least 4 years.
i'd have to get the air cleaner off to have a look.

-----
re injectors and question of where fuel is coming from the engine runs on at present.
there is a very quick test you can do with the state the car is in.
bypass the cold start injector.
it should be in line in the circuit between the right and left banks of injectors.
undo the fuel hoses to it. then join them together. sleeve it and clamp or if you have nothing to sleeve them together maybe a piece of leftover fuel hose from your replumbing. use that to join the left and right hand banks and by pass the cold start injector.

fire it up. see if anything changes. like does it go.

---

you will be taking the injectors out to do the seals soon.
will be an opportunity to observe the injectors.
get them all out but leave them connected to fuel circuit.
stick the nozzles into 4 small bottles.
those really small plastic bottles that water comes in are handy.
they seem the right size to perch down there in the engine bay and then you can usually get the injector nozzles to nicely fit into them to spray.
that will tell you if they are all spraying.
just crank the starter. they should all fire if they are any good.
you can crank it for a bit. say 20 seconds or so.
see if the same amount of fuel is in each bottle.
see if they are spraying equally.
its a kind of rudimentary test.
but it will at least tell you if they are working.

Posted by: technicalninja Mar 12 2023, 12:55 PM

Smoke test is a good idea at this point.

I had one last year that threw me for a loop.

550K 2000 Toyota T100 Tacoma, 4-cylinder 5 speed.
1 owner from new. No engine problems ever. On original clutch.

Had 1 injector go bad 20K in past, lost another 3 weeks before the problem.
Changed all 4 with real OEM Densos (hard to find).
Injection was L-Jetronic style with upgrades that happened due to 25 years of technology changes.
L-Jet with MAF, waste spark, real potentiometer TPS, O2 sensors, OBD2 but still simple batch fire injection.

Truck is run 150 miles per day from Granbury to Southlake for work. Owner has been doing this forever.
Truck runs fine on freeway but anything below 40 mph it's a sick chicken. Bucking, snorting, an absolute bitch to use stop and go. NO Idle at all. Seemed possessed.
Fuel pressure 5 psi below normal. Changed regulator. Fuel pressure normal but didn't help the issue. No check engine lights or codes in memory.
Did a bunch of diagnosis to no avail. Figured out that a brand-new $4K Snap-On Solis scan tool could not see live data actually live. It had a 5 second delay in reporting data.

Decided I didn't have a scan tool that was quick enough to actually see what was going on in "real time" or maybe I'm a moron and cannot diagnose FI problems anymore.
Charged customer for FPR and 1 hour of diag time. Spent 2 days fighting this beast.
Super good customer that brings me ALL of their cars and all of their friends and extended families cars.
"A" class people, the type of customer that keeps your business alive. Horrible to say "I can't fix this" to this type of customer.
Leaning towards bad ECU but I've never had a bad ECU Japanese car that would actually run. Bad ECU=dead puppy in my book.
I "ate" this one big time.

Referred them to Toyota Dealer with the hope that one of the old dogs at the dealership had more direct experience with these than me.
One of the 20+ year techs had two of these himself, shitloads of experience and he could use his two trucks for swap and check diagnosis.

$1300 later they figured it out.
They swapped everything including my brand-new injectors. Nothing helped it. They swapped all the old stuff back into truck.
They finally did an ethanol test of the fuel and found 42% ethanol...
Not 10 or 15%, they found 42%.

Drain and re-fill gas tank fixed this truck completely. It was the root of the issue.
The gas looked and smelled fine, and it was less than a couple of days old, but it was still bad.

After the diag was complete the customer told me he's been filling up at the same gas station for 20+ years but there was an accident at the gas station that day and he was forced to fill up at a different station just before it did this crap.

I should have questioned the fuel from the start. It was a screw up on my part.

Current fuels cannot be "stabilized" with additives. Unless you can do a full lab analysis you should not trust fuels over 6 months old.

Lots of my customers who own classic cars use race gas in them. This fuel, with no ethanol or "green" additives can last 5 years but it costs over $10 per gallon.

Nest door to me is a big Lawn Mower dealership. They are about to hit their busiest season as spring brings massive fuel issues because the mowers have been stored for the last 4 months not in use. 33% of their yearly business is cleaning out old pump gas from fuel systems.

The OP has not said how old the fuel is, just that it is good.
I don't trust fuel anymore; it has made me look like an idiot too many times...


Watched the videos. The TPS looks fine, my AFM flap does not have the play at rest that the OP's does. Mine is ancient and has not been rebuilt.
One thing, I'm not sure the tach is accurate. It's hard to tell via a YouTube vid but it sounds like 2K when it shows 3.5k. I'd verify the tach is accurate with an old school engine analyzer. I have a 40-year-old Craftsman DIY unit that can give me dwell and RPM readings. I pulled it out from a 30-year hibernation to check dwell on my ignition the other day. I've almost thrown it away a couple of times and I'm glad I kept it now.

From the run vids his injectors are delivering fuel IMO. The 7 min long video kills the idea that he's running on the cold start injector in my book.
After starting the cold start injector could be disconnected to prove this. I think it's running on all 4 injectors now. You can listen to the injectors "click" with a mechanic's stethoscope but I'm betting they all are. You can kill the cold start injector by disconnecting it or by disconnecting the thermo-time switch.

The vid that shows the resistance change via the AFM flap almost looks like that drops out (seeing infinity) at different points in its travel. This would cause major issues and might be the source of his trouble. I use little jumper cables with tiny little alligator clips so I'm not trying to hold the leads on the pins in the AFM when doing a resistance check to verify I don't have a bad spot on the AFM printed circuit board. The resistance change should also be a slope with no dropouts to infinity or direct continuity ever.

Hope this helps.
I am very interested in what the root cause of this problem is.

The info I've posted makes it look like I hate ethanol...
This is far from the case.
E85 or E100 is a super fuel that is dirt cheap. It's equal to 105-110 octane racing fuel when run in modern systems that are designed and mapped for it. The final engine in my current 914 will have modern digital EFI and E85 will be my "preferred" fuel for it.

What I don't like is the addition of 10-15% ethanol in normal pump gas. It doesn't help anti-knock at that level, the corn used for production increases the cost of pretty much everything in the grocery store, and it doesn't clean up the tailpipe emissions at all as the fuel economy drops enough to offset the gains via increased overall mass in the exhaust.

In gasoline it sucks, as a stand-alone fuel it's rocket fuel...
Even at 85-100% its long-term storage life sucks big time. Ethanol needs to be brand new in my book.

Posted by: wonkipop Mar 12 2023, 01:35 PM

@http://www.914world.com/bbs2/index.php?showuser=27135

i just watched his 7 min film.

hmmmm.

certainly interesting.

fricken weird.

i'd have to think about it.

i note it managed to hit 4K revs at one point there racing away.
and he got it to drop to 1200 clamping off the AAV.
but it seemed a bit all over the place.
not quite consistent.
would have to watch it again and look closely at what revs were at different times he had both hoses on. i guess that could depend on just how tightly a hose was clamped off each time. but it did seem at one point as if it was doing 3000 rpm with both hoses connected and at another point 4000. ?

yes i doubt a cold start injector stuck on with nothing else injecting would deliver 4K revs.

Posted by: wonkipop Mar 13 2023, 07:33 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

i watched your clip again a couple of times.

right just keeping it simple.

1. cold start problem.
put that aside for the moment.

2. fast "idle" racing problem.
put that aside for the moment.

3. the big one. it won't take applied throttle.
you can overthink this sometimes.
i just watched the video with an open mind.
its not getting fuel.
plain and simple - the fuel just cuts out.

why?

not sure.
but it is most certainly connected to it knowing the throttle has been opened.
two ways that happens.
the TPS sends the signal (or stops sending the signal more accurately) for idle.
the AFM takes over.
(until you hit wide open throttle).

i still think the screw up is in there somewhere.

something is happening where once the car comes off the idle position on the TPS, it goes looking for the info from the AFM and its not there so it just shuts it all down. closes the injectors off. when you take your foot off the throttle immediately the minute it begins to stall the switch comes back on again and so does the fuel. and the engine just manages to come back to life. leave your foot on there too long or double pump it and its a stall.

i don't exactly know how. you have checked the TPS switch. and you have checked the EFI harness for integrity. so ????

but it seems very clear to me that its getting fuel (might be running like a mad banshee) but its getting fuel while the throttle is closed.

and as soon as that switch comes off, no fuel.

i don't think its a fuel mixture problem. like leaning out.
its a absolute mixture problem. its all air?

like technicalninja says, don't think thats down to blocked injectors.
they seem perfectly capable of propelling things to 4000 rpm.
they could be a bit shitty but not so shitty i think that they would suddenly fall over.


i have not had a chance to run into mike yet to see if he had any clues.

-------

Posted by: Van B Mar 13 2023, 09:49 PM

Too be clear fellas, the injectors don’t have to be blocked. If the flow rate increase turn the injector into a stream, it won’t atomize correctly and the car will stall… and also smell very rich.

But I’m not certain thats the issue either, just a theory.

In post #1 he says, car would stall with throttle, then messing around he blew the AFM and had to replace it, then ran normal, then racing idle and stall with throttle again?

Posted by: wonkipop Mar 14 2023, 03:07 AM

its a good theory.
not discounting it.

the trouble shooting issue i believe condenses down to this.

car will start and idle.
stalls when throttle opens.

subset two of trouble shooting.
car is difficult to cold start.

i believe having watched the video that it may be possible to make this thing idle.
the moment where he crunched the line to the AAV and it dropped to 1200 was an eye opener!. i am still processing how it can run at 3000-4000 off an AAV and a decel.
and then squeezing one line it dropped to 1200. hmmm.

i'm going to take all this to mike and ask him. casually when i next get to the workshop to continue adventures in 1984 thunderbird land. (i actually like working on the thunderbird because it always make me think of chief crazy horse, my favorite indian warrior when i was a kid. his warpaint was all about the thunderbird. rain on one cheek lightning bolt on the other. the indigenous mob in america were cool cats )

like @http://www.914world.com/bbs2/index.php?showuser=27135 i think i want to know what the root cause of this debacle is.

i still have not interrogated the full history of exactly how this emerged.
when.
and in what sequence.
i mean did @http://www.914world.com/bbs2/index.php?showuser=4426 wake up one morning and it just had all gone to sh$t when he started it. i don't think so. but we can get to that. what happened along the way to here.

Posted by: wonkipop Mar 14 2023, 03:25 AM

i am actually interested in @http://www.914world.com/bbs2/index.php?showuser=4426 's car.
same month of production as mine.
about a thousand vins before mine.
same gorgeous brown vinyl.
same brown carpet.
teamed up with green. he has the @http://www.914world.com/bbs2/index.php?showuser=10753 combo.

its a little more worn.
but examining his engine bay photos surprisingly intact.
tune up sticker is still there all in one piece.
i even spied his emission sticker in one post.

i think he needs to tell us more about this car.
where he got it.
his plans for it.
its an L jet.
i know he wants to supersede that and go all fako 2.0 d jet...........but.

all in good time.

and i watched his video having fun at watkins glen.

so ...........happy to try and sort this problem.
the car has my sympathy.

Posted by: wonkipop Mar 14 2023, 02:38 PM

ok.
i can see how that can happen.

throttle closed theoretically fuel pressure is down at 28lbs with vacuum from plenum. throttle opened, vac comes off, fuel pressure rises to 35lbs.
he has confirmed he has those two pressures.

with you theory it floods due to injector flow rate changing.
wet plugs would confirm that if he shut it down straight after he induces a stall rather than letting it recover and run. immediately pull the plugs and inspect.
as i note you have previously suggested.

only time injectors do have decreased flow rate is at idle and at deacceleration after throttle closes. so it does fit the scenario. open throttle fuel pressure rises, flow rate increases, spray pattern goes to sh#t. ok.

his only real way to confirm the injector behaviour is to take them to a specialist for testing and with luck cleaning.

this business with high ethanol content in USA fuel could induce pintel corrosion if you lay the car up for long enough. it is hygroscopic. if the pintels are corroded its throw them away time. they never come good even with attempts to clean. any relief is temporary.

fortunately here fuel with ethanol (which is permitted up to 10%) must be labelled E10 and we still have wide availability of petroleum without the blend.

Posted by: tshih914 Mar 14 2023, 04:45 PM

i think he needs to tell us more about this car.
where he got it.
his plans for it.
its an L jet.
i know he wants to supersede that and go all fako 2.0 d jet...........but.

all in good time.

and i watched his video having fun at watkins glen.

so ...........happy to try and sort this problem.
the car has my sympathy.
[/quote]

Here's the story of my 1974 914-1.8L. I bought it from a person who lived in Manhattan NYC who advertised in craigslist during circa 2000? He was asking $4000 and the car was not running because the alternator warning light was lit and he thought he needed to get a new alternator. I suspected that it could be that or the belt had broken and I asked him how much it was costing him to keep the car parked at his apartment's garage. He said his monthly garage fee was $350 and that his mechanic said it would costs him about $1000 to replace the alternator. I made him an offer of $2500 for the car and he took it after I told him if he doesn't sell the car in another 3 months he would be worse off than selling it now for $2500.

When the car was towed home to NJ courtesy of AAA I discovered that it was indeed only a broken fan belt which I replaced for $50 and it ran like well without issues. I drove the car as a weekend toy as I had a 1990 Honda Civic base hatchback 4speed manual daily commuter. The body was in very good condition except for the battery tray having been replaced due to acid damage and some minor structural rust along the back lower valance area that I repaired by welding (badly) pieces of steel to cover up any holes and gaps between rust through. The dash has a crack which was covered over by a plastic cover and it looks decent enough to not be a problem. I was not content with its performance compared to my 1st 914 (a 65,000 miles 1974 Signal Orange 914-2.0L w/appearance group) which I had purchased used for $6000 in 1979 while at Caltech getting my PhD in chemistry. I had a desire to perhaps upgrade my 1.8L L-jet to the more reliable and higher output D-jet 2.0L. I searched and found a 1975 2.0L which was F/S because it also was in a state of disrepair (broken fuel lines spraying fuel all over engine bay when attempted to start and the body was very rusty. I bought it for $1000 in 2003(?) and stripped it for the parts (engine with complete F.I., 901 gearbox side shifter, set of anti-sway bars and door handles). I then sold the rolling chassis to some kid who wanted to make 1 good 914 from 2 chassis for $650. The engine after being stripped down to the split case halves and crankshafts in 2008 is finally being reassembled with brand new 2.0L Mahle pistons and cylinders new rod bearings and main bearings, rebuilt heads, new NOS stock Porsche camshaft and modified swivel feet adjusters (valve train).
The interim period where my 1.8L was parked due to lack of attention since I had many other Porsches to drive and enjoy started to develop a hard starting problem. This was indeed due to being parked for over several months with fuel that was going bad due to the switchover to ethanol in place of MTBE. The reason ethanol is bad for cars that run well on pure gasoline is it soaks up water over time and gets oxidized to gummy polymers and wreaks havoc as our friend techninja had described. Being a chemist I am well aware of this problem so I have been careful to make sure the gas in my tank is well preserved with Marine Stabil when stored after my having to rebuilt my blown AFM.

The whole thing about using ethanol in gasoline is the result of complete political capitulation to the corn lobby as it is scientific lunacy to add something that is completely unnecessary for the efficient and clean operations of the internal combustion engine. The idea of adding an oxygenated additive was to aid in the combustion process when carburetors were crudely metering out fuel in the 1970s. Today's ICE can burn all HC fuels completely to CO2 and H2O without the fuel having any oxygenated additives. A gallon of pure gasoline produces the maximum amount of energy and goes the greatest possible distance compared to a gallon of pure ethanol of anything else (E10, E85, etc).

The whole Climate/global warming existential threat is a complete hoax and cult to destroy the American global dominance and cede every advantage to China.

Getting back to my problem I will do the injectors test for flow and spray pattern soon in the upcoming weekends and report back.

P.S @http://www.914world.com/bbs2/index.php?showuser=24231 The car at Watkins Glen is a 2020GT4 (grandkid to the 914?)

Posted by: wonkipop Mar 14 2023, 07:56 PM

@http://www.914world.com/bbs2/index.php?showuser=4426 .

cal tech man. i'm impressed.
and driving a 914 back then. man of taste.
my business partner is a chemical engineer.

-----

ok i spoke to mike finally.

here is what you do.

now that we have discovered the AAV and decel issue they must now be taken 100% out of the mix for further trouble shooting.

pinching the hoses is not adequate. thats merely a initial test to note that you can lower the revs closing them.

1. pull decel hoses as previous test. plug them at the ports with 100% sealing plugs.
the decel valve is not to be hooked up again while the trouble shooting work is being done. it is not required for this work.
you can reinstall it later if you succeed in adjusting it properly. at the end of everything else. we know this drops the revs 400-500 going off your video.

2. pull and plug the AAV hoses. mike did not think that the huge drop in revs you were getting at times by clamping it was out of order. cold it is wide open. and since we know its stays wide open the warmer the engine gets the faster it can run on the fuel being made available to it.

3. in consideration of the hard starting you could start the engine and warm it with the AAV connected if this helps to start it. then stop the engine. disconnect and plug the AAV at the ports and the hose. probably most convenient where it connects to intake duct.

4. ensure the timing is correct. this can be done statically. it is surpsingly accurate if set this way. so long as you know what you are doing. if the timing is out, setting it statically will get it closer to where it ought to be than where it is now.

5. check the points gap. it is essential that the points are clean and set precisely.

6. check that the accelerator cable is not pulling the throttle plate even open slightly when you have it connected up. ensure that throttle plate is completely back at rest on its stop and not being even cracked open a little bit.

7. what you are going to be doing is manipulating the AFM flap by hand with your fingertips while the engine is running. in the case of a 914 due to the air cleaner design and AFM location you will find it best to unbolt the AFM from the upper aircleaner it is attached to but still connected to the air intake boot. you need to be able to get your hand in a comfortable position to be able to gently manipulate the AFM Flap for what is ahead. it will probably be necessary to get the rest of the air cleaner out of the way/

8. it is essential that the idle is lowered as far as possible for this exercise.
there seemed to be promise that with those hoses effectively plugged and engine fully warmed it might drop as low as 1200 rpm. if its still to high - say 2000 rpm try and bring it down by adjusting the idle screw on the throttle body. do it in small amounts.
and give it time to settle between each small adjustment.

9. play with the throttle in the engine bay. get used to finding a comfortable position where you can manipulate it very gently opening it small amounts and opening it slowly.
do this with out the engine running. just find out how you can position yourself.
what you are going to be doing is manipulating the AFM flap with your left hand and the throttle with the right hand while leaning into the engine bay. so you need to work out where to position the AFM and prop it and where to position yourself and do all this.

------

A after timing is set, points checked, decel definitely out and plugged. start the car with the AAV still connected if you think this will help. let the engine warm for at least 5 minutes. if you want to control it a bit and lower revs pinch the AAV hose shut and just let it run as low as you can get it until its warm. you will feel the engine heat and know its hot enough.

B. switch off. disconnect AAV and plug the hose and port 100%
restart. hopefully it can without AAV assistance once its warm.
if necessary lower the idle further if its still high at say 2000. get it down as low as you can. it might go unstable due to further air leaks we haven't found yet. ie it will lean out. just back it back off again if it does. go for as low as you can get it to be.

C. once its idling at whatever you can it to. hopefully somewhere down there between 1200 and 1500 its time to play with the AFM. push it in very gently and very slowly very small amounts. what you are doing is tricking the ECU to deliver more fuel.
you are changing the mixture. we want to see if the ECU is getting the AFM signal.
the throttle will still be closed and we will have taken the major air leak routes out, so the revs and tone of the engine should change if the AFM is working and also communicating.
remember very small manipulations. you will get the hang of it and can play around a bit with it.
if it does respond we go to D.
i have always been uncertain about this bit as i believed the throttle position switch controls the mixture at idle. and it does. but mike says, like Van, that if the AFM flap moves far enough it will provide info too. usually it does not at idle because it is not being pulled far enough to override the idle circuit in the ECU.

D this is where you are going to crack open the throttle and play with the AFM at the same time. now you don't want to open the throttle wide and suddenly. you want to crack it open and hold it open a little bit. and then if it falters push the air flow flap a small amount as well. see if you are able to keep it running. if you can keep working up the scale. a little more throttle - a little more AFM flap.

-------

why are we doing this.
its to see if in fact @http://www.914world.com/bbs2/index.php?showuser=26011 is right.
Van is basically saying this thing has a mixture problem in very crude terms.
its not getting anything like enough fuel out of the injectors once the full pressure comes on. EDIT - more properly Van is saying its not getting its fuel delivered in the correct way as an atomized mist pointed in the right direction as well as possibly not giving the full flow rate at throttle open fuel pressure. but you can trick it to prove this.

mike agrees with Van. he is not saying this is necessarily the cause but the above test will certainly tell you whether it is or not and it will also affirm the AFM is working and communicating.

the problem you have got is you are way up there in revs at the moment at "idle"
and then you are wanting to open the throttle and the AFM is actually at a point lower down the rev mountain (in terms of fuel and air). so we need to be doing this test from a point where we climb the rev mountain if possible with the throttle rather than fall off the cliff if that makes sense.

anyway this test is going to tell you a lot.

it might take you a few attempts to master this given the fickle state of its idle and its cold start problem.


----

as to cold start difficulty.

timing. timing. timing. points gap. points gap. points gap.
and is the cold start injector working.

-----

as to badly spraying injectors.
not just flow rate.
i got a lecture on where the injectors might be pointing whatever spray pattern they make. correctly functioning injectors are pointed directly at the back of the valve where it seats. vaporization in a warmed engine completes the job atomization has done.
if they are spraying anywhere else at other surfaces fuel won't vaporize effectively.
etc etc. unhealthy injectors can produce a whole series of difficulties of which Van B is only hinting at because he knows what it all means just like mike does.

------

see how you go with this.
at least you will be able to feel confident with your AFM after this if it works.
and also your AFM to ECU connections.


-----
As an aside L jet is as reliable as D Jet and far simpler.
Its just a matter of making sure all the components are working to spec.
running well an L jet is real sweet in my humble opinion.
not that there is anything wrong with a D Jet 2.0 either.

Posted by: tshih914 Mar 18 2023, 11:42 AM

I started to follow your test and have posted some new short video on my pfan12000 youtube channel. I managed to get the idle down to about 1200rpm and at step 7 was about to do the static timing check of the points under the distributor cap and remembered that a while ago I had replaced the mechanical points with a Pertronics electronic ignition system (see photo below). So unfortunatelyafter shutting off the engine I was not able to restart it to get it to idle at 1200 rpm before testing the AFM/throttle position switch. I believe that the electrical ignition system is normal but the problem most likely is going to be localized around the AFM settings. In my attemts to restart the engine I was loosening the idle control screw at the base of the throttle housing and was still not able to get a sustained 1200 rpm idle even with the screw completely out.


Attached thumbnail(s)

Posted by: Jason74914 Mar 18 2023, 03:49 PM

Are you using factory high pressure fuel pump or something with similar pressure and liters per minute?
Are you sure the input and return lines to the pump are properly installed?
High idle sounds like vacuum leak (smoke test) or bad AFM.
Cutting out over 3k rpm sounds like fuel delivery issue. Not enough pressure and/or flow rate.

Posted by: Jason74914 Mar 18 2023, 03:55 PM

Just saw your last posted. Inability to restart after it was running could be fuel pressure regulator, which holds fuel pressure for a while after you shut down so that you hav some on restart. But vacuum issues also affect FPR.

Posted by: wonkipop Mar 18 2023, 04:11 PM

thats what we will find out with the test i have given him to do.

he has got good fuel pressure and it is correct (with both vac line to FPR off and on).
but it is an interesting point (re return lines etc). i don't know if he has an original three port fuel pump. all we know from his replies is it has been shifted to the front and it is direct wired in to run when ignition is on, rather than stock set up with fp run off the AFM flapper contacts and dual relay).

it did have big leaks. they were through the decel and the AAV so were metered air that was affecting the AFM flap. these appear to have been the primary leaks.

it may still have other leaks but these will be unmetered leaks.
he has been given suggestions of where they commonly will be and to replace various seals. ie injector seals. etc.

-------

i watched video @http://www.914world.com/bbs2/index.php?showuser=4426 .
it almost sounded normal.
so at least we know with that decel and AAV taken out 100% you can get it very close to normal idle. and that these are the major sources of the air leak side of things.

to restart you may have to reconnect the AAV.
warm it if it will start.
disconnect.

points gap and static timing were to be done before you started the engine again.
don't know petronix. someone who has it can comment.
i guess point gap is non issue.
static time it is all you need to do. or check the static timing.
timing sounds like its very close to correct listening to that video.

-------

if you can get it restarted and get it idling like that again then you will be able to get to the point of doing the AFM and throttle manipulation test.

the idea of that test is to tell you if you may well have a fuel delivery problem with the injectors.


EDIT

ii just took a very close look at the photo you posted @http://www.914world.com/bbs2/index.php?showuser=4426 .
have you noticed that the green vac line hose is disconnected from the back of the distributor retard side of the double vac can.

did you just knock this off getting distributor cap off? or has it been off the whole time?n

this is another air leak. your engine will be pulling in air via the vac port on the throttle body through that hose.

this is unmetered air.

that hose has to be reconnected.

i've seen people disconnect that retard vac line and therefor disconnect vac retard.
not sure thats a good idea, but theoretically it can be done.
but you would have to either plug the hose or plug the port on the throttle body.

Posted by: tshih914 Mar 18 2023, 04:38 PM

The green hose was connected during the whole time engine was running. It was disconnected when I took the cap off to show you the Pertronic ignition system.

https://www.motortrend.com/how-to/1404-pertronix-performance-products-ignition-systems/

above website explains the replacement of traditional points and condenser with electronic ignitor

Posted by: wonkipop Mar 18 2023, 04:43 PM

ok

Posted by: wonkipop Mar 18 2023, 04:50 PM

@http://www.914world.com/bbs2/index.php?showuser=4426 .

the point is you are making progress.
using elimination.
dont get distracted. don't shot gun it.
lots of comments come in here that are well meaning but have not read the whole thread. its 10 pages!

just do the test with the AFM and the throttle - if you can restart it and get it going again.

report the results.

--------

the hard starting issue can be looked at later.

it could be a separate problem or it could be related to the issue of injectors.
we will get to that rationally.

----------

don't assume anything about the AFM yet.
its a new rebuilt unit.
we have to assume its good for now.
given that you report the car did run well for a time with it installed.
but later developed these problems we are addressing one by one.

Posted by: wonkipop Mar 18 2023, 07:29 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

watched a couple of the other films which look like some newer ones you have put up since i last looked.

one in particular.

so looks like you had it down at steady 1200.
so this must have been after you managed to adjust idle with AAV and decel 100% out.

then you must have resumed with AAV clamped off with vice grips.
it was sitting at 1200.
then you were gently applying throttle directly by hand on t/b.
and it was dying as you gently opened up throttle.
correct?
but if you backed off the small amount of throttle quickly it resumed.

and then you unclamped the AAV and it died.

if you can get to that same state again and start manipulating the AFM flap to see what happens it will be interesting.
you need to disassemble the AFM meter from the upper part of plastic aircleaner so you move the flap with your fingers easily and in small amounts. it will be too hard trying to poke a screwdriver at it with any sort of dexterity.

Posted by: technicalninja Mar 19 2023, 10:16 AM

I just take the black plastic top off of the afm to manually operate it.

Now, back in my Z car days I ALWAYS kept a known good AFM as a test item. It's buried in 10K lbs. of Z-car stuff right now...

A couple of days back I tried to "slope" my not-proven good 914 AFM.

As the test in the past, it doesn't really slope accurately.

I never see infinity or continuity through it but the resistance values vary back and forth across the range so right now I cannot say that testing an AFM with a DVOM is a good way to verify operation..

Sorry I couldn't be more helpful with bench testing an AFM.

Posted by: wonkipop Mar 19 2023, 02:53 PM

this test i have told him to do will tell him enough to zero in on it.

he should not need to open the black plastic top on the AFM.
you can operate it easily once its off the air cleaner.
four bolts. no need to break the AFM seal.
also if the need arises to return the AFM it will also be clear he has not tampered with it.

one of two things are going to happen when he starts manipulating the AFM.

1. nothing.
that means either his AFM, his EFI loom, or his ECU is kaput in some way.
he has tested the loom at the plugs and it seemed to be ok.

2. something. the engine will respond.
which means his problem likely lies somewhere else.

it really is looking to me like there is something wrong in the AFM, the loom, or the ECU having watched his video where he had the revs down to 1200 and very gently opened the throttle. when it comes off that idle switch in the throttle body it really feels as if its a no signal situation.

but the test i have told him to do will point to that if its the case.

Posted by: tshih914 Mar 22 2023, 07:54 PM

[OK just uploaded my 6 min 29 sec video of the AFM and throttle test on my pfan12000 youtube channel. View it and open for comments

Posted by: wonkipop Mar 22 2023, 11:58 PM

not entirely clear what you did watching that film.

test was.
1.
first push the flap without touching the throttle.
did anything happen?

2.
manipulate throttle along with AFM flap and see if you could keep it going?

you will need to fill me in that this is what you did.
and if so -

what happened at 1?

i think you were doing 2 for most of what i was watching on film.
didn't look like you could keep it going.

without you reporting on 1 i can't tell you what you are looking at here.

Posted by: tshih914 Mar 23 2023, 05:42 PM

Sorry wonkipop, I forgot to establish a baseline idle of 1200rpm before playing around with the AFM flap. At the end of last weekend's attempt after getting the 1200 rpm baseline idle after engine had warmed up and plugging all manifold openings connecting the AAV and decel valve I noticed that the hose plug going to the rear of the decel valve had popped off so I used a hose connector this time to connect the manifold hoses together. This time the car started on the first attempt and reached about 3000 rpm which dropped to 1800 rpm when I disconnected the hose to AAV.

I just tried to repeat test 1. after establishing an 800 rpm idle. You can see video at 3:52 and around 6:20 I was able to raise rpm to around 2000 by moving the flap of the AFM . When trying to move throttle along with the flap the stalling occurs but the engine can be restarted immediately. The video is uploaded on my youtube channel it's about 8 min long.

Posted by: wonkipop Mar 23 2023, 08:52 PM

great

i watched film.

i believe there is nothing wrong with your AFM - you just proved it. test 1.
its communicating with the ECU.
mind you thats an opinion but that is what i believe.

what you are doing there is basically commanding more fuel.
but if its all healthy leak wise it should not be getting additional air to go with it. so its a tricky little operation where you have to have a deft hand.
you did the test well.
it will want to flood the engine which it sounded like a couple of times.
but you managed to be sensitive enough with it to raise revs with the available air flow to prove the AFM is in action.

it raised revs a fair bit. more than i thought it would. will talk to mike.

second.
you have proved what is playing a big part in sending the idle sky high.
defective AAV. responsible for a fair whack of those elevated revs.
probably to the tune of 1200 worth when its cold and running enriched off the ECU at cold start.
defective decel valve. looks like its worth up around 800 rpm worth in same situtation.
you will have to find a way to get a fix on that.
there have been suggestions in relation to both items.
with them out of the picture and well sealed off, and a bit of tweaking on the idle air screw (with additional tune up, ie valves and timing) there should be no reason it won't idle steady at the spec rate of around 900 + or - 50.

your throttle body needs re-examination. in particular the tps.
i'd be concentrating on that to see if it can rectify the situation.
but i'll wait to speak to mike.

the car also sounds a ways out of tune.
sounds like it needs a valve adjustment.
timing set properly.
plugs checked, cleaned or replaced.

Posted by: wonkipop Mar 23 2023, 10:04 PM

mike just rang me.
so i spoke to him.
recited the rev rise you got out of the AFM from the low idle of 800.
you said you got it to 2000 pushing in the AFM.

his comment, (and he would know) is you still have significant air leaks.
you managed to give it fuel and there was sufficient air to support 2000 rpm.
he feels if the system was leak tight you would only get a rev rise of about 50-100 rpm before it fell over with a gentle push of the afm.

so you are still chasing other leaks in his view.
since you have new hoses etc.
there are three main places left.

the intake runner gasket sleeves that connect to distributor plenum.
you can hose clamp those.
injector seals.
intake manifold gaskets/seals.
(to do the last one you have to get the intakes off).

finally a smoke test.

after that once its leak tight.
and its still doing some hesitation its got to be to do with the TPS.
it could still be playing a part.

another place to look for leaks is the throttle body itself.
the bushings on the throttle plate pivot axle.
not much you can do about that without a full rebuild.

as a question.
this 800 rpm you got it down too.
did you adjust the idle screw.
if so. how far down.
is it still off the bottom or have you screwed it down shut.
i'm remembering early on this the idle screw was closed entirely.

Posted by: wonkipop Mar 24 2023, 12:12 AM

further question.
when you say it would start immediately.
this was with the AAV shut off completely and the decel vavle isolated and closed off?


i can tell you this system is entirely intolerant of any air leak.
after i recommissioned mine the throttle body gasket gave up the ghost.
it was half a century old.
i was quite astonished by the degree of unstable idle and inability to idle from this tiny air leak. new gasket kindly supplied by an aussie site member and away i went.
problem gone.

as you close off the obvious sources of additional air its going to go find the other ones that are there and are available for it to suck air through. it induces them in fact. which might explain why its all over the place a little bit. its looking for air leaks. the more you tighten it up the more it wants to find whats weak. same as capilliary water leaks into buildings.

anyway, there are still some air leaks there to find in yours.
but you are getting closer on that front.

Posted by: tshih914 Mar 24 2023, 03:46 AM

@http://www.914world.com/bbs2/index.php?showuser=24231
The engine indeed needs a full tune up and new spark plugs and probably a new CHT sensor replacement as well as all the other old seals that you mentioned as potential sources of air leaks.

To get the 800 rpm idle I had to adjust the idle adjustment screw 2.5 turns off bottom position. AAV blocked off and decel valve rear and side hoses blocked.

The throttle body seal is newly replaced when I was checking the throttle switch and terminal. Thanks to you and Mike we are making tremendous progress. Greatly appreciate the methodical troubleshooting approach being applied to this problem.

A question regarding the throttle body mechanism : what is the role of the upper part which consisted of a concentric lever that is connected to a spring off the back wall of the engine bay?

Posted by: wonkipop Mar 24 2023, 04:35 AM

if your accelerator cable fails or the throttle spring itself fails (the one coiled on the mechanism) it pulls the throttle closed.
throttle safety spring.
it all goes in the opposite direction with the rear engine VW engines. you will notice there is a little hole in the seam of the air distributor plenum on the upper seam. thats for hooking the spring into on the rear engine VW applications of the same engine.

i watched your film a second time.
you managed to actually match the AFM flap to available air there at the point where you got it to 2000 approx rpm. it actually sounded alright. sounded smooth! you were there. was it sweet for a moment?
its a video and not really the same as being there, but for a moment it sounded sweet. like you were the human intervening in the out of sorts infant proto electric "intelligence" that was very upset and having a tantram, and you kind of fooled it into something close to the correct air fuel mix. which was the idea of the test. glad you could be persistent and have a go at it. its easier using your fingers with the air cleaner off and not a screw driver. i've watched mike do the same thing with an AFM on a 964. he diagnosed a bent flap on that along with some other issues, so i knew what he was talking about when he instructed me to tell you to do this procedure. the 964s have the same fragile AFM flapper as the old 914s!!! not that there is necessarily anything wrong with your AFM. he did do it with mine when he was fooling around really tuning it up at one stage.
i just let him do it. but he was playing with the AFM flap. that was a few years back when we were bringing it back to life. its an olds hands trick. some of the guys here would probably know how to really do it. its all part of playing with it when you are timing the car and tuning it up.

according to him the air leak saga goes on forever. you plug one and then the greedy engine goes looking for the next faded jaded connection and just blows her open. or sucks it open to be technically correct. you do get to the end of it. you can pre-empt it by simply doing them all to start with as others here have suggested. despite you plugging off AFM and AAV real tight i think now its finding the other weak links. so you will have to chase it all down. its an old girl. she is half a century old.

i didn't have any of these problems on raising mine from its coma as i just went right through it before the attempted start and renewed every hose and tested every component amongst a lot of other things. but the throttle body gasket i walked right past and it turned around and bit me. it just went after the one thing i had not renewed and chewed it up and spat it out.

Posted by: wonkipop Mar 24 2023, 05:18 AM

there is one more spot where 1.8s can leak air.
the valve cover gaskets. (or rocker covers as some folks call them).

we glued the gaskets on to the rocker covers with something mild.
i'll ask mike what he used. its an old trick.
its not an aggressive adhesive. i can't remember what it was.
it was his trick. i never had to do it on my old squareback as it was not fuel injected.

if it was leaking air there it would probably be leaking oil from there as well.
although an oil leak there can be confused with a push rod tube o-ring seal leaking.
which they can also leak air through. but there is going to be a bit of an oil leak involved to spot that. puddles on the floor. lots of oil smoke burning off the heat exchangers.

Posted by: Geezer914 Mar 24 2023, 05:55 AM

I second Wonkipop suggestions. I have left 2 posts telling you to do a smoke test. Stop beating your head against a wall and do it. Ljet high idle is vacuum leaks! Check the large tube from the AFM to the throttle body for cracks.

Posted by: nihil44 Mar 24 2023, 06:47 AM

Please re visit post #75. I have spent 8 months or so chasing vacuum leaks and I offered my experience of the journey in a spirit of community in the hope that it will put you in the fast lane with this operation.

Please re visit the post. I hope the information will help. Some effort goes into making posts of this nature (photos, re sizing photos etc).

My favoured method/s would be pressure testing with soapy solution or bubble mixture as recommended by the factory or using the same technique except applying vacuum.

Good luck and I hope you some level of satisfaction when you expel the evil spirit of vacuum leaks

Posted by: wonkipop Mar 24 2023, 05:22 PM

@http://www.914world.com/bbs2/index.php?showuser=4426

you were asking about rest position of AFM thousands of pages back.




yep thats how it should be.
(or we are both stuffed )
note the orange 3 bond sealant.
the work of my old german mechanic from must be 30 years ago.
still holding up.
he was fanatical about ze hair leekz in ze luft-troneek as he used to call it.




and the other end since i had it out.

Posted by: wonkipop Mar 24 2023, 05:32 PM

@http://www.914world.com/bbs2/index.php?showuser=14058 .

i have a feeling he will be looking up post #75.


hows your rig going. you got to the bottom of ze hair leekz yet?
ze joyz of zee first space hage teknologee az ze components get older zan ze pyramids.

bet you the current generation of cars don't get as far as the old 914s before all that plastic adorning the engines shizers itself.

Posted by: tshih914 Mar 24 2023, 06:01 PM

@http://www.914world.com/bbs2/index.php?showuser=14058

I will certainly try your ingenious method of post #75 after I refresh all the old connection seals and valve cover gaskets and fuel injector seals etc and will use compress air via schroeder tire stem valve and soap solution to find any leaks.

Posted by: nihil44 Mar 24 2023, 07:18 PM

@http://www.914world.com/bbs2/index.php?showuser=24231

Was supposed to do a track day 2 das ago but shift link bushing at firewall coupling disintegrated on the way. Bit of a long story but I assumed that the bushing I installed was a Delrin one, mainly by the colour but it was made of some soft crappy material which failed in the most bizarre way.

Car is now running well overall but still pursuing a stumbling issue. I am satisfied the vacuum leaks have been dealt with. The most surprising one was the failed inlet manifold gaskets. That is why I posted urging @http://www.914world.com/bbs2/index.php?showuser=4426 to re visit my post on vacuum leak testing. It was a long journey for me and I hoped that my R & D would put him in the express lane.

Posted by: Porschef Apr 1 2023, 08:05 AM

I’ve not read through this entire thread but I totally agree with the smoke test suggestion; it’s very easy with a machine and will immediately point out air leaks. I had a couple, one was at an exhaust flange.

However, Ljet vacuum leaks do not create a high idle condition, it’s quite the opposite. (Djet will) I’m running Ljet on a 2056, 9550 cam and a 123 distributor. Until I eliminated all vacuum leaks it wouldn’t idle properly, and there’s a multitude of places for that to happen.

Posted by: tshih914 Apr 1 2023, 08:07 PM

Sorry for the lack of progress, lot's of things coming up like tax filings and other priorities in life also start of track driving season. Today I went to Lowe's and got some plastic pipe fittings (2 inch diameter) to make into the tool that improves on nihil44's design. Posted a short video testing the tool on the old gaskets and seals. This is shown on my pfan12000 youTube channel. I still haven't the time to change out all the seals and sparkplugs and fuel injectors seals before final check for leaks.

Posted by: tshih914 Apr 1 2023, 08:09 PM

Attached tire valve stem.

Posted by: tshih914 Apr 1 2023, 08:20 PM

My youTube short video shows minor leaks at the intake runner seals and at the idle adjustment screw at the base of the throttle (expected). Will need help from another person to check again after new seals are installed.

Posted by: nihil44 Apr 1 2023, 11:41 PM

@http://www.914world.com/bbs2/index.php?showuser=4426



Pleased you got a result.

Posted by: tshih914 Apr 27 2023, 06:50 PM

Finally got some time to continue searching for any vacuum leaks and doing a proper tune up with new sparkplugs and seals for injectors and intake plenum gaskets. Going this weekend to Carlise Central PA swap meet to buy seals for 914. The old sparkplugs that I removed looks like cylinders 1,3,and 4 are heavily running rich with lots of soot (see photo.)

Posted by: tshih914 Apr 27 2023, 06:57 PM

After doing some additional research and running across a YouTube video of someone who was trying to revive a Toyota Fast and Furious race car that used E85 that was sitting for 8years I decided to get the F.I injector cleaning and testing machine from Amazon to check out my 914's fuel injectors. Will have to wait till Saturday May 6 to remove and test my injectors.

Posted by: wonkipop Apr 27 2023, 07:04 PM

now you are having fun. keep up the good work.
you will be an L jet expert by the time you finish.

Posted by: technicalninja Apr 29 2023, 08:37 AM

Oh, WOW! an inexpensive fuel injector test bed that also says "ultrasonic cleaning" and "Reverse Flow"
Holy sheep shit, Batman!
I'm going to get one!!!

Till I read the customer review on the 6 cylinder model.
I do a lot of 6 cylinder stuff...

Lets see if it will copy over...
____________________________________________________________________

This product is definitely cheaply made. During first use hade to fix leaks everywhere and the pump burned up within 10 min. And started shorting the machine out. It clogged 4 brand new injectors up that I was using for just testing purposes on operating the machine. My guess there was trash in the system from factory assembly. Luckily I have a small repair shop and have seen this pump before on a yamaha hpdi. So after after a complete overhaul by me the machine works as it should with a much more reliable pump. The reason I went above and beyond with this machine is one I really wanted one for my shop and 2 Amazon didn't want to give me a return with direct replace and I don't know why because the company still hade plenty. They just wanted to give me a refund and then I could reorder.

______________________________________________________________________

The 4-cylinder model has a very good review, but that review "reads" like a technician wrote it. Spelling screw ups and bad grammar are completely correct for the type.
I should know...

I own a business and I have been contacted (through the US mail ONLY!) by a company that sells positive reviews. Some of my competition suddenly had 200 reviews instead of 40 and they had changed from below 3 to well above 4.5.
I don't trust simple reviews anymore...
That review looks "legit" to me.

I'll wait and see how well you do with it.

Please let us know how it worked.

I would have taken Amazon up on their offer at least one time before rebuilding it myself. Not sure why he didn't...

Personally, I'd run that first with nothing installed and clear any debris that may be present...

Posted by: tshih914 May 6 2023, 06:44 PM

Well your wish has just been granted.I took out all 4 injectors of which 2 inner seals look suspect and have new seals to reinstall after testing. The machine came with very little info on how to assemble and use but any mechanically inclined person can figure out how to set it up. The way in which the fuel rail gets sealed to the inlet of the injectors requires a rubber O-ring that gets compressed down by the fuel bar and O-rings were not provided with the unit. The posted photo shows a green O-ring that was used to seal the adapter to the top of the injectorand when I tried to replace the #2 injector with a 2.0L injector that O-ring seal was not in place or was distorted) I went to Harbor Freight and got a box of assorted size O-rings. As you will see on my YouTube pfan12000 channel there were some short videos where I had problems with leaks and such which were corrected. Overall the machine did as advertised and I am quite satisfied with the results of running those tests (02 setting is idle speed , 03 is medium speed, 04 is fast speed, 05 is acceleration, etc). It appears my #2 injector is not spraying like the other 3. I will try to sonicate that injector to see if it can be cleaned to work like the others.


Attached thumbnail(s)

Posted by: tshih914 May 6 2023, 06:58 PM

The tests showed that injector #2 was spraying or leaking much more fuel than the other 3 so when given throttle that injector most likely flooded that cylinder and messed up the fuel/air ratio that stalled the engine.


Attached thumbnail(s)

Posted by: rhodyguy May 7 2023, 06:37 AM

Witch hunter charges $23 for cleaning and flow resting per injector. How much did that fancy machine, that seems to have failed out of the box, cost? Small flat rate priority box, $10 iirc, and done.

Posted by: tshih914 May 7 2023, 10:57 AM

The problem I had initially trying to set up the machine was getting the fuel rail feed to seat properly onto the injectors. The green O-rings I used were not right and I had lots of leaks that were fixed by using the brown Viton ones that were the right size as shown in the photos.
I paid $500 for CT200 from Amazon Prime. I used it to clean all 4 injectors and got them to behave the same through-out all ranges of flow rate (idle, medium, fast, and acceleration). Checking the web for new or re-manufactured injectors that would work for 1974 914-1.8 found them on PartsGeek for $62 each + shipping is going to cost at least $250 for a set of 4.

feel free to check out my latest short videos on my pfan12000 YouTube channel


Attached thumbnail(s)

Posted by: wonkipop May 7 2023, 04:33 PM

injector tester looks like a fun machine. ultrasonic cleaning bit is useful. if you have enough cars to worry about cleaning injectors! anyway, sounds like you diagnosed one of your major problems. getting closer to a good running Ljet.

i paid about $60.00 USD each for a set of bosch injectors 3.5 years ago.
a reasonable price for NOS. but make sure they are still in sealed plastic bags with pintel caps. check the rubber hoses. if they were stored well they should be good.

believe it or not the injectors were around $60.00 in 1990! i looked up an old invoice.

Posted by: Geezer914 May 8 2023, 03:41 PM

Rock Auto 1.8 Standard Motor Products injectors!