Last Lemming

Ok. I’m about to dump this car off the cliff!

I’m sooooooo discouraged!

This whole process started because I couldn’t get the idle to drop to spec. I assumed a vacuum leak. I used a smoke machine and hooked it up to various vacuum lines and when I finally hooked it up to the line that ran to the AOS I go smoke coming out what appeared to be the bottom of the AOS. Seemed like a good bit was coming out too. I couldn’t actually see and verify the smoke was coming from the bottom seal, I just saw smoke coming out that general direction.

I just put everything back together this morning, started the car, and no difference, same exact problem!!!!

so I just redid the smoke machine and I’m not getting smoke from the same spot on the AOS. So that’s good I suppose. However, if I pinch the hose going to the ICV, the RPMs dropped where they’re supposed to be. (Stuck ICV??)

So you would think “oh you have a bad ICV”, except that I replaced the ICV less than 50 miles ago trying to illiminate this issue, thinking it was the ICV. I also replace the computer and all the hoses that lead to it in from the ICV.

Only thing I haven’t really tested is the wiring going to the ICV.


Any help would be appreciated.

T&T Racing

Suggest separating the J Boot and looking inside. If oil is present, then this confirms along with smoke test that the AOS seals are leaking, letting excess unmetered air into engine intake. *** is to replace the seals.

Last Lemming

Sorry, if I wasn’t clear, I just took the whole thing apart to replace the seals so those are new and I’m still having the issue

V2Rocket

Is the throttle bypass screw adjusted down? Throttle stop screw? Have you leak checked the throttle body itself?

jhowell371

Have you checked the J-boot for cracks allowing unmetered air in?

Last Lemming

The TB has been fully rebuilt and tested for leaks, as for the J boot I run a Vitesse set up so I have a metal boot.

inthink the problem resides with the ISV system. I can pinch off the vacuum line going from the charge pipe to the ISV and the RPM drop to the correct speed. That tells me the problem should lie in the realm of the ISV. Is this ISV open??? IDK.

I changed out my old ISV with my current new unit in hopes of solving this issue but the problem still remains. I replaced my DME as well chasing this. Problem still remains. The only thing left is the wiring in between these systems, however after a brief look at the wiring schematic I’m not sure how I would go about testing it. I do know that when I use a jumper at the test port the idle speed does not change.

Zirconocene

Do you get the same problem (or fix) if you just unhook the connector to the ISV? It's possible that you have a short there that is doing wacky things to the operation of the ISV.

Good luck (and keep on this, you'll get it fixed)

walfreyydo

Lets not assume your ICV is bad, since you just replaced.

High idle indicates more air getting past the throttle valve than its supposed to. Yes that could be the ICV, but it is more likely your idle adjustment screw (8V motors only) - so this could potentially be a very easy fix... https://www.clarks-garage.com/shop-manual/fuel-08.htm

Background/justification: 8V cars do not have a variable ICV (like the 16V cars), its binary, so it either fully opens or fully closes. Also the 16V cars lack an idle adjustment screw and idle is fully controlled with the variable ICV. So again, more than likely your ICV is working fine, and air is getting into the intake through somewhere else (hence the assumption its your idle adjustment screw being adjusted too high).

Also based on this, you should also check your TPS and verify you are getting the "click". Clarks has plenty more info on testing the TPS. The DME only activates the ICV if it detects that the TPS/Throttle is closed (ie at idle).

Tiger03447

Gents, recently I had my AOS off the engine block and tested it by blowing into the large hose connection at the top. It wouldn’t hold pressure and was blowing out under the cap. So I put flowable permeated silicone all around the joint. All this means I had a vacuum leak there. I was also appalled that the two metal fittings under the intake manifold were loose as well. Some locktite and silicone will fix this as well. Three more vacuum leaks cured!

walfreyydo

The correct fix would be to replace the upper and lower O ring on the AOS and replace the seal on the oil fill cap.

Gage

"The TB has been fully rebuilt" could be a clue. If the throttle blade was removed (a must for a rebuild), it could very well be installed out of position, either backward or simply not in alignment with the bore causing air to bypass when in the closed position. Remove the TB and hold it up to a light source to check the fit.

Tiger03447

The cap that I was previously referring to was the one that the AOS hose connects to that has to be pried off. There is a o-ring there also, but it is not listed in the PET. This top is the one you have to remove to clean out the main chamber of the AOS. Sorry I wasn’t clear enough the first time. Mea Culpa.

Last Lemming

I have verified the function of the TPS to be working correctly. I get the click, the multimeter test checks out, and the Vitesse software shows it to be working when I run the program.

I thought of the throttle blade as well, but it is solid and appears to be functioning correctly.

to me the clue lies in the fact that if I simply pinch the hose leading to the ISV the RPM corrects itself. This would also seem to eliminate the TB as a culprit.

im beginning to lean to a short in the wiring but I’m not sure how to test this. I know there are 3 wires, just not sure what I’d be looking for.

if there was a short and the ISV was stuck on open wouldn’t that cause a high idle RPM?

Last Lemming

Also if I want to test the wiring I need to understand the schematic.

here is the schematic can some answer the questions in red. That might help a lot.

walfreyydo

Idle

Adjustment

Screw


Have you checked it? I linked the clarks garage instructions on adjusting two posts ago.

Pay attention... Pinching the hose reduces the air flow coming into the intake, and your idle is too high because too much air is currently allowed into the engine. This is why pinching the hose to your ICV fixes your idle issue, because you are artificially reducing the amount of airflow. Stop going down rabbit holes and just try adjusting the screw before proceeding any further.