Aopsahl7

1986 Vette L89.

The problem I am having is the really high idle. When I first start it up it sits around 8-900rpms. After a little bit of driving it gets to the point where if I dont even give it any gas with my right foot it will bring the car up to about 40mph. When I come to a stop it feels like I am holding on the brakes and trying to accelerate at the same time. It sucks.

If I come to a stop and shift out of drive into neutral it will rev up to about 2000-2200 rpms without touching the gas pedle at idle. Then of course when I put it in drive it jumps into gear and is ot a very nice ddrop into gear. I am afraid if I keep this up the tranny is not going to like me.

Anyways I am thinking that this is due to some vaccuum leak. I took off all the emmissions stuff like the air pump and such. Where do I start and how do I diagnose?

Thanks!

GREGGPENN

I'd probably use unlit propane to see if you can find the leak. Failing IAC can also cause that.

Dr.Huxtable

Whens the last time you've cleaned your Throttle Body? Might give that a shot also. I just cleaned mine the other day and it was horrendous. could also be the ICV like he mentioned ^ how many miles are on the car?

sailorsteve

The fact that the idle is more or less normal at cold start would lead me to suspect something other than a vacuum leak. On cold start, the ECM is in "open loop" and ignores voltages from the IAC, TPS, etc. and uses default values. When the car warms up, the ECM goes to "closed loop" and uses inputs from the various sensors.

GREGGPENN

Good point. I gotta agree with you on that. Kinda makes me think the IAC won't close up enough or the TPS isn't measuring correctly.

If you had a USB <==> ALDL cable, you could download TunerPro or TunerCat and see what was going on. Not sure if a scanner can do that.

Makes me wonder if you can remove/plug the IAC to see what it does (after warm-up).

AGENT 86

What did you do with the vacuum lines to A.I.R. Valves ?
Did you plug them ?