Re: 1988 CIS 930 Turbo 3.3 (need help)

[dnowak]

If the car has been sitting for a day...it starts right up. It will idle perfectly for about two minutes...then it dies. You can restart it...but usually with some difficulty...but it will always eventually start. You can drive the car...it runs fine...except for the fact that if you put the clutch in and brake...the car will die. Bottom line...the car dies when you let off of the gas...will not idle on its own...you must heel & toe while under braking. Where do I start looking for the problem here?

Modifications to car: Stainless steel headers and exhaust (no catalytic converter) sport cams, 8:1 pistons and cylinders, crank fired ignition (recently installed three new coils)...1.0 bar...(79,000 total miles).

[full quack]

Sounds like you have a vacuum leak. Check your aux. air valve to be sure that the little internal disk is closing off when it's warm. Sounds like it is stuck full open. Your aux. air valve is located right next to you W.U.R. and has the 1 big hose going in to the right side of your intercooler, and 1 hose going to the manifold.

Mark

[mark houghton]

Originally Posted by dnowak

If the car has been sitting for a day...it starts right up. It will idle perfectly for about two minutes...then it dies. You can restart it...but usually with some difficulty...but it will always eventually start. You can drive the car...it runs fine...except for the fact that if you put the clutch in and brake...the car will die. Bottom line...the car dies when you let off of the gas...will not idle on its own...you must heel & toe while under braking. Where do I start looking for the problem here?

Modifications to car: Stainless steel headers and exhaust (no catalytic converter) sport cams, 8:1 pistons and cylinders, crank fired ignition (recently installed three new coils)...1.0 bar...(79,000 total miles).

Might be WUR control pressure issues, and you can test that without the car running....but you'll need the gauge setup if you don't have it. Possibly running too lean at cold - but rich enough to run decent until the WUR heats up and leans it out even more.

You may also have a vacuum/air leak. Check hoses and particularly the intercooler seals. I blew a seal once while boosting down the road and had to heal/toe it to keep it running at idle. Really messes with your fuel mixture.

Have you tried turning the idle up with the idle adjusting screw? If you can get it to at least idle when hot, then you can begin to trouble shoot causes (such as spraying carburetor cleaner around all seals to see if the rpm changes, indicating a leak).

Do you have an AFR gauge setup, or access to a CO sniffer to check your mixture at idle?

[mark houghton]

Originally Posted by full quack

Sounds like you have a vacuum leak. Check your aux. air valve to be sure that the little internal disk is closing off when it's warm. Sounds like it is stuck full open. Your aux. air valve is located right next to you W.U.R. and has the 1 big hose going in to the right side of your intercooler, and 1 hose going to the manifold.

Mark

I would agree on the vacuum leak as the most probably culprit, especially if this condition just suddenly reered it's ugly mutated head. But that AA regulator - if stuck open - would probably cause a perpetual high idle. If he can get the thing to idle long enough, a simple hose pinching at the AAR might tell something.

Yep, lots of places for phantom air to get in on these things and very frustrating. I think the next time I pull hoses and seals and such, I'm just gonna goop a bunch of high-temp silicone rubber caulk around everything for a permanent seal and be done with it

[full quack]

Definitely try the hose pinch approach if possible, that would be the fastest way to confirm or eliminate the aar.

Mine had gunk build up in the slot that the disk travels in, and finally it stuck wide open, and she would not idle when warm. Took it off the car & cleaned it with carb cleaner, problem gone.
Maybe I just got lucky???

Mark

[h20cooled7]

On mine the harness for the safety switch on the side of the air meter was melted to the tin. Age and running hot I guess. But the wire would open and cut out the pumps. Ran a new wire with ground.