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slotty008
Hi guys ,
I just hope that someone could help us with the idle of my '75 2.0. I have the car for almost 7 years now and idle was always a little bit too high. We have been trying to correct this but it got worse instead of better. We changed the distributor to a 123 ignition, we changed all the vacuumlines, the AAR has been cleaned out and the idle screw is completely closed.
The car starts at 1600rpm when cold and once it is warm it goes to 3000rpm and the idle stays there. The car pulls very well , a lot better better than when I just had it. confused24.gif confused24.gif confused24.gif
BeatNavy
I'm going to say you have:

a. a vacuum line disconnected or routed incorrectly, and/or

b. the wrong curve picked for the 123 dizzy -- when I installed mine I had to use one with vacuum retard, not advance, option off the throttle body -- otherwise I ended up with a situation like yours, and/or

c. your timing is just too far advanced

Lockwodo
QUOTE(slotty008 @ Jul 24 2022, 02:29 PM) *

Hi guys ,
I just hope that someone could help us with the idle of my '75 2.0. I have the car for almost 7 years now and idle was always a little bit too high. We have been trying to correct this but it got worse instead of better. We changed the distributor to a 123 ignition, we changed all the vacuumlines, the AAR has been cleaned out and the idle screw is completely closed.
The car starts at 1600rpm when cold and once it is warm it goes to 3000rpm and the idle stays there. The car pulls very well , a lot better better than when I just had it. confused24.gif confused24.gif confused24.gif

Sounds like a vacuum leak. If the vacuum lines have been replaced, then possibly the PCV valve if so equipped is stuck open, or the AAR is open. Or a manifold leak.
wonkipop
test the AAR after the car has completely warmed (and is hitting 3000 rpm) by squeezing the hose tight to close the hose. revs will drop if its a stuck open AAR.

you say you cleaned it. does not mean its working.

a little bit of difference between AAR on a D Jet and an L. i have an L so someone else who knows would tell you how to properly test a D Jet AAR.

does sound a little bit like the AAR is stuck open and is not closing.
trouble shoot it to tick it off.

good luck.

other thing might be decel valve needing adjustment.
idle vacuum is able to pull it open if its spring pressure has become weak.
this is something that has come up on L jets - not sure about D Jets.
adjust it via the nut on one of the hose nipples.
cgnj
Broken intake gasket. Paid big dollars in the early 80s to not have this diagnosed. That when I decided to fix my own cars.

Carlos
Rand
3k? Definitely a huge vacuum leak. Timing can't be advanced enough to do that without some serious issues. Follow the air path...
Head, phenolic blocks, injector seals, plenum.... You get the idea, any potential place for air to get in BELOW the butterfly. But 3k is like a major hose disconnected.
emerygt350
Yeah, 3k is way too high for AAR as well. Get yourself a can of carb cleaner and start spraying. When the idle drops, you found your leak. Take some pics of your engine bay and we can take a look at that routing. That year should have passive pcv if I remember correctly.
porschetub
QUOTE(BeatNavy @ Jul 25 2022, 10:05 AM) *

I'm going to say you have:

a. a vacuum line disconnected or routed incorrectly, and/or

b. the wrong curve picked for the 123 dizzy -- when I installed mine I had to use one with vacuum retard, not advance, option off the throttle body -- otherwise I ended up with a situation like yours, and/or

c. your timing is just too far advanced

agree.gif but the idle screw hard and fast also sad.gif another red flag with a false air idle like that it has to be one of the larger hoses ..thinking AAR also.
slotty008
Thank you guys for all the suggestions. I'm gonna call my mechanic today and we're gonna check it all out. Closing the AAR tube was already something I wanted to do.
If we can't solve it , I'm gonna send some pics of the vacuum lines.
To be continued...

Robin
slotty008
My mechanic picked up the car this morning and this afternoon I picked up a backup switch at the Porsche Centre in Antwerp. I had an aftermarket switch before but it was crap. Tomorrow I'm gonna have a look in the shop to see if we have any progress.
emerygt350
QUOTE(slotty008 @ Jul 25 2022, 05:59 AM) *

My mechanic picked up the car this morning and this afternoon I picked up a backup switch at the Porsche Centre in Antwerp. I had an aftermarket switch before but it was crap. Tomorrow I'm gonna have a look in the shop to see if we have any progress.


Does your shop know much about d-jet injection specific to the 914 and its changes across years? It's the kind of thing that one of us that have done it could probably fix/diagnose in minutes but would cost 1000s for a shop to learn/throw parts at etc.
VaccaRabite
Go find my thread on making a home-built smoke machine and smoke testing your entire intake tract. You WILL find the source of your intake leaks that are giving you a high idle. You will need to put some cellophane (kitchen plastic wrap is what I used) between the throttle body and the boot for the air intake box or all your smoke will just go out that way. With that huge hole covered, there is nowhere for the smoke to go but out the leaks you have. With the boot covered, ANY smoke in your engine bay indicates a leak. You may need to dig to find where it is, but you have one - and it may not be something obvious like a vacuum hose.

For me it wasn't at all obvious before the test, and clear as day after. I had a worn out throttle body. I would never had found that without smoke testing. I've also seen rust holes and cracks in the plenum. Bad gaskets. All sorts of issues.

I built the smoke tester for under $40.

Here I made it easy. This is the link to the thread:
http://www.914world.com/bbs2/index.php?act...=2&t=353039

Zach
dr914@autoatlanta.com
if the thottle is completely closed then you have a vacuum leak, a line is off the runners are not sealed to the heads or plenum and or the decel valve aux air valves are sticking


QUOTE(slotty008 @ Jul 24 2022, 02:29 PM) *

Hi guys ,
I just hope that someone could help us with the idle of my '75 2.0. I have the car for almost 7 years now and idle was always a little bit too high. We have been trying to correct this but it got worse instead of better. We changed the distributor to a 123 ignition, we changed all the vacuumlines, the AAR has been cleaned out and the idle screw is completely closed.
The car starts at 1600rpm when cold and once it is warm it goes to 3000rpm and the idle stays there. The car pulls very well , a lot better better than when I just had it. confused24.gif confused24.gif confused24.gif

StarBear
popcorn[1].gif
Rand
George chimed in with nothing that wasn't already said. George, pay attention.
Slotty, read the posts and share what you do along the way so we can keep helping you. Job #1, find and fix the vacuum leaks.

slotty008
Update,
This afternoon I got a call from my mechanic. We have some progress, thanks to all your comments.The AAR is not working properly.When he shuts off the AAR line , the idle drops to 1200rpm when cold and 1600rpm when warm. That's already better but still way too high.He thinks there's a leak in the throttle valve or maybe the axle is worn. I don't know if these are the appropriate terms since I'm not English speaking, but I hope you understand what I mean.
He already tried to repair the AAR but it still doesn't work . He proposes to eliminate the AAR and fit an electric valve that I can shut down when the engine is warm. Is this a good idea? Hope to hear the comments from the experts.
To be continued.
Robin
StarBear
AARs are available. One sold here just a few days ago. Big thread on testing and maintaining the a few weeks ago. If can find, also indicates comparable Nissan part #.
Lockwodo
QUOTE(StarBear @ Jul 29 2022, 03:52 PM) *

AARs are available. One sold here just a few days ago. Big thread on testing and maintaining the a few weeks ago. If can find, also indicates comparable Nissan part #.

agree.gif best to replace the AAR. It progressively closes as an internal heating element warms up, versus an electric valve would be open or closed. You can also take an AAR apart and may be able to free up the mechanism. There's a you tube video on that.
brant
Sounds like he suspects the bushings holding the butterfly/shaft in your throttle body are worn.

Easy enough to check

And most of the throttle bodies are worn out on these djet cars by now
wonkipop
QUOTE(StarBear @ Jul 29 2022, 04:52 PM) *

AARs are available. One sold here just a few days ago. Big thread on testing and maintaining the a few weeks ago. If can find, also indicates comparable Nissan part #.


you are thinking of our L jet AAV @StarBear . different beast.

@slotty008 has a D Jet. i've read those AAVs are next to impossible to find/buy.
i think its a kind of rotary style design. don't know much about them.

sounds like your mechanic is on the ball @slotty008 .
throttles wear out on L jets. don't think the D jet version is any different.
they get wear where the throttle plate rests against the interior bore of the throttle body and the axle shaft and bushings wear.

StarBear
Ahhh. Didn’t pick up on that. Thanks!
slotty008
QUOTE(Lockwodo @ Jul 30 2022, 12:14 AM) *

QUOTE(StarBear @ Jul 29 2022, 03:52 PM) *

AARs are available. One sold here just a few days ago. Big thread on testing and maintaining the a few weeks ago. If can find, also indicates comparable Nissan part #.

agree.gif best to replace the AAR. It progressively closes as an internal heating element warms up, versus an electric valve would be open or closed. You can also take an AAR apart and may be able to free up the mechanism. There's a you tube video on that.

I've seen the youtube video. I cleaned out the AAR a couple of months ago and it closed when I put current on it. My mechanic already took apart the AAR 2 times several weeks ago,apparently with no result. We'll see next week when the throttle is repaired. unsure.gif unsure.gif unsure.gif
wonkipop
QUOTE(slotty008 @ Jul 30 2022, 02:05 AM) *

QUOTE(Lockwodo @ Jul 30 2022, 12:14 AM) *

QUOTE(StarBear @ Jul 29 2022, 03:52 PM) *

AARs are available. One sold here just a few days ago. Big thread on testing and maintaining the a few weeks ago. If can find, also indicates comparable Nissan part #.

agree.gif best to replace the AAR. It progressively closes as an internal heating element warms up, versus an electric valve would be open or closed. You can also take an AAR apart and may be able to free up the mechanism. There's a you tube video on that.

I've seen the youtube video. I cleaned out the AAR a couple of months ago and it closed when I put current on it. My mechanic already took apart the AAR 2 times several weeks ago,apparently with no result. We'll see next week when the throttle is repaired. unsure.gif unsure.gif unsure.gif


yes @slotty008 - i've got a theory on these old AAVs and them seeming to work when you test them.

i will qualify this by saying mine is a 1,8 L jet which has a different design of AAV mounted directly on the engine block.

i cleaned and tested mine 2.5 years ago and yes it seemed to work.
but what i have retrospectively thought is that i had it out of the car and i tested it on a bench.

i now wonder if the cold engine block conducted cold into the body of the AAR means that when installed on the engine, and with an age weakened spring that it just can't warm up and close like it did new. so it sort of sits there. in fact in my case its jammed closed.

i did have a really weird thing happen about 2 weeks ago when it actually worked.
thats because here in australia we have been having record cold temps. somehow i think it was so cold that it caused the AAV to contract open past some point it had been sticking at - maybe due to a small ridge of corrosion.

they are very fickle at this point in time half a century down the track. beerchug.gif
slotty008
Update: I ordered a throttle body gasket and the rubber to the airfilter. My mechanic installed them today but the problem is not gone. headbang.gif He thinks that the throttle valve is worn( axle and bushings) I suppose throttle bodies are no longer available so is it possible to repair this? wacko.gif
DRPHIL914
QUOTE(slotty008 @ Aug 9 2022, 02:57 PM) *

Update: I ordered a throttle body gasket and the rubber to the airfilter. My mechanic installed them today but the problem is not gone. headbang.gif He thinks that the throttle valve is worn( axle and bushings) I suppose throttle bodies are no longer available so is it possible to repair this? wacko.gif



yes they can be rebuild and have new bushings installed, there is a member here that does this service. Phil i believe, he rebuilt my with all new stuff a couple years ago.

Smoke machine would help you find any other leaks, but also with d-jet, if you are running lean you will have a fast idle.

Phil
rjames
Throttle body is likely worn to some degree (they all are by now if they haven't been repaired), but I would still do as Zach and Phil suggested and do a smoke test.

Also, if you haven't already, remove and plug all of the vacuum hoses except for the one going to the MPS. If the idle drops significantly, add them back one at a time until the problem returns. If the idle doesn't drop significantly, the problem lies elsewhere- like the intake runner gaskets or a cracked plenum.
slotty008
Update:
By the end of August we finally had some result. My mechanic took the AAR apart again and it's working now. But we still have a minor vacuum leak on the throttle body. Rpm when cold is between 1400 and 1600 but it drops to 1000rpm after a few minutes. I can live with that. I tried to find someone in Europe to fix the throttle body but no succes so far. I also found a new throttle body in Germany but it was so expensive...
BTW, do all 914's have the same throttle body?
In the mean time , I made some long test drives and everything works well. biggrin.gif biggrin.gif biggrin.gif
76-914
QUOTE(slotty008 @ Oct 31 2022, 07:37 AM) *

Update:
By the end of August we finally had some result. My mechanic took the AAR apart again and it's working now. But we still have a minor vacuum leak on the throttle body. Rpm when cold is between 1400 and 1600 but it drops to 1000rpm after a few minutes. I can live with that. I tried to find someone in Europe to fix the throttle body but no succes so far. I also found a new throttle body in Germany but it was so expensive...
BTW, do all 914's have the same throttle body?
In the mean time , I made some long test drives and everything works well. biggrin.gif biggrin.gif biggrin.gif

Do you have an airport near. Throttle body shaft bushings are a common problem on light aircraft engines. A good A&P can take care of that quickly. As a side note: If one inadvertently connects the Oil Temp sending wire where the CHT sender wire should be connected you will have a 3500 rpm idle - warm or cold! Ask me how I know. headbang.gif
Dave_Darling
QUOTE(slotty008 @ Oct 31 2022, 07:37 AM) *

BTW, do all 914's have the same throttle body?


No, they do not.

All of the 2-liter 914 throttle bodies are the same, but the1.7 and 1.8 ones are a different size and sit sideways rather than straight up-and-down. I think the 1.7 ones are different from the 1.8 ones as well, but I'm less sure on that.


Can you please ask your mechanic if he has a smoke machine? This has been suggested at least four or five times so far in the thread--for a good reason. It can help you find exactly where leaks are.

Really, seriously. SMOKE MACHINE. Fill the intake with smoke and see where it comes out. You really really want to know where the problem is rather than firing the "parts cannon" at the engine and hoping the problem goes away.

--DD
wonkipop
QUOTE(Dave_Darling @ Oct 31 2022, 07:03 PM) *

QUOTE(slotty008 @ Oct 31 2022, 07:37 AM) *

BTW, do all 914's have the same throttle body?


I think the 1.7 ones are different from the 1.8 ones as well, but I'm less sure on that.



--DD


yes 1.8 is a different throttle body in detail than a 1.7.
slotty008
QUOTE(Dave_Darling @ Nov 1 2022, 02:03 AM) *

QUOTE(slotty008 @ Oct 31 2022, 07:37 AM) *

BTW, do all 914's have the same throttle body?


No, they do not.

All of the 2-liter 914 throttle bodies are the same, but the1.7 and 1.8 ones are a different size and sit sideways rather than straight up-and-down. I think the 1.7 ones are different from the 1.8 ones as well, but I'm less sure on that.


Can you please ask your mechanic if he has a smoke machine? This has been suggested at least four or five times so far in the thread--for a good reason. It can help you find exactly where leaks are.

Really, seriously. SMOKE MACHINE. Fill the intake with smoke and see where it comes out. You really really want to know where the problem is rather than firing the "parts cannon" at the engine and hoping the problem goes away.

--DD

My mechanic still doesn't have a smoke machine, but I have all the ingredients for making one myself. I'm gonna put everything together but I have another job to do first:put extra isolation on my attick dry.gif dry.gif
slotty008
Now that I'm retired, I've finally found the time to finish the smoke machine. I used a pickle jar, 2 car valves, an old bicycle pump, a 10€ soldering iron and an old tube from a tire pressure pump. I had to seal the car valves and the soldering iron with Tec-7 because too much smoke escaped there. I mounted a lid from an aerosol can on the tube of the tire pressure pump. It fits exactly on the throttle body. smilie_pokal.gif Yesterday we did the test and a little smoke is escaping along the axle of the throttle valve. So I will have to look for a better throttle body or find someone to repair it. All the vacuum lines were tight.

Click to view attachment
slotty008
Click to view attachment
VaccaRabite
Mine leaked at the same place. Ended up replacing the entire throttle body.

Zach
76-914
Those can be re-bushed. Is there such a word? Any machinist can do it. It will need to be drilled out then reamed for a proper surface for the new bushings. Don't try this yourself because the surface must be perfect and final reamed with a reamer that is .001" undersized for a press fit. You can also go to a local airport and find the A&P who works on small aircraft that will do this for you. beerchug.gif
emerygt350
On my car the idle screw even leaks when fully closed. Maybe I will get around to rebuilding it this year. At least it's easy to pull and work on. Luckily it leaks exactly what I need for the car to idle where it is supposed to.
slotty008
After disassembling the AAR several times, I gave up. Once installed , everything went fine until the next day and then it jammed again. So I constructed a system with a solenoid valve instead of the AAR that I can open or close from the cockpit. I open it when I start the car and after two minutes I close and I have a 1000rpm idle. It's not perfect because it's all or nothing but certainly better than an unreliable AAR.

Click to view attachment
slotty008
Here it is installed.

Click to view attachment
slotty008
I've put a box on it to protect it. The bottom of the box has been cut out.

Click to view attachment
slotty008
And this is the knob in the cockpit.

Click to view attachment
rjames
QUOTE(76-914 @ Mar 18 2023, 08:12 AM) *

Those can be re-bushed. Is there such a word? Any machinist can do it. It will need to be drilled out then reamed for a proper surface for the new bushings. Don't try this yourself because the surface must be perfect and final reamed with a reamer that is .001" undersized for a press fit. You can also go to a local airport and find the A&P who works on small aircraft that will do this for you. beerchug.gif


I was able to do this at home. Not hard if you’re careful. If I can do it, anyone can.
emerygt350
QUOTE(slotty008 @ Mar 24 2024, 09:33 AM) *

And this is the knob in the cockpit.

Click to view attachment

I like it!
rhodyguy
Do not overlook the stacked elbow. Kind of an obscure part in an obscure location. The rubber portion can crack/split.
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