[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?
Full Version: 1974 1.8L engine fast idle then stalls
ok @tshih914 .
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 @StarBear 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 @emeryGT350 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.
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 @StarBear 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 @emeryGT350 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.
AAV FS in classified FS/WTB forum, as Van B highlighted. $65. Unsure if working?
@tshih914
you mean this arrowed.
its just an engine tin screw and washer.
Click to view attachment
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 @Van B did take his out and replace it.
he might have some tips if you are lucky.
you mean this arrowed.
its just an engine tin screw and washer.
Click to view attachment
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 @Van B did take his out and replace it.
he might have some tips if you are lucky.
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.
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.
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.
QUOTE(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.
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.
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.
Click to view attachment
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.
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.
Click to view attachment
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.
QUOTE
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.
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.
@Van B
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.
Click to view attachment
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!
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.
Click to view attachment
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!
QUOTE(technicalninja @ Mar 11 2023, 09:40 PM)
QUOTE
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.
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.
yeah you are right.
i'm backwards on that.
another naturally dyslexic moment.
QUOTE(technicalninja @ Mar 11 2023, 07:40 PM)
QUOTE
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.
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.
I posted a bunch of videos and shorts on my YouTube channel @Pfan12000 .
link here: https://studio.youtube.com/channel/UCmLvtTxokU7diByRQaSm46Q
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.
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.
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.
Regardless, you have yet to confirm the timing, or assess the plugs after running the engine.
QUOTE(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.
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 @Van B
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?
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
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
@tshih914
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.
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.
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%
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%
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…
@Van B
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.
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.
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...
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...
@technicalninja
i'm digesting your comments.
experience on J fuel injection totally relevant.
nippon EFI was faithful J implementation of krautrock systems.
i'm digesting your comments.
experience on J fuel injection totally relevant.
nippon EFI was faithful J implementation of krautrock systems.
@technicalninja - 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.
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.
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...
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...
QUOTE(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 $150.00 years ago.
I wonder if you can still get tanks cleaned?
All the radiator shops have gone out of business...
sh$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.
QUOTE(wonkipop @ Mar 12 2023, 01:29 AM)
@technicalninja - yeah i just read through your big post up above.
i can see why you call yourself a ninja now.
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...
QUOTE(technicalninja @ Mar 12 2023, 01:48 AM)
QUOTE(wonkipop @ Mar 12 2023, 01:29 AM)
@technicalninja - yeah i just read through your big post up above.
i can see why you call yourself a ninja now.
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...
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.
here you go mate. @technicalninja
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$t.
you need to get into the phantom agent mindset to crack L jet.
no use being an american/aussie trying to tune a carby!
shintaro. (not really my scene when i was 7 years old).
https://www.youtube.com/watch?v=-eVZHgBkMWI
back to krautrock fuel injection.
these diversions are important.
there is lots that can screw up in L Jet of a mechanical nature.
which @Van B reminds us of.
i found it.
you can find anything on youtube.
phantom agents. aussie kids were obsessed with this circa 1965.
we would wear plastic breakfast bowls on our heads trying to copy this stuff.
https://www.youtube.com/watch?v=t2_tMhgisd8
more conservative kids were into SHINTARO.
he was your typical historical samurai figure.
but no way was he a ninja.
phantom agents were the sh$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 @Van B reminds us of.
Not to be redundant, but did you do a smoke test and check the intake runner gaskets???
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?
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?
QUOTE(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?
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.
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.
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.
@technicalninja
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.
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.
@tshih914
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.
-------
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.
-------
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?
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?
QUOTE(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?
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 @technicalninja 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 @tshih914 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.
i am actually interested in @tshih914 '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 @StarBear 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.
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 @StarBear 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.
QUOTE(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?
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.
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 @wonkipop The car at Watkins Glen is a 2020GT4 (grandkid to the 914?)
@tshih914 .
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 @Van B 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.
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 @Van B 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.
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.
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.
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.
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.
QUOTE(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.
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.
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i watched video @tshih914 .
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.
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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 @tshih914 .
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.
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-pert...nition-systems/
above website explains the replacement of traditional points and condenser with electronic ignitor
https://www.motortrend.com/how-to/1404-pert...nition-systems/
above website explains the replacement of traditional points and condenser with electronic ignitor
QUOTE(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.
ok
@tshih914 .
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.
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.
@tshih914
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.
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.
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.
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.
QUOTE(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.
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.
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