Sometimes (really intermittent, not predictable as far as I can tell) when I start my car the idle is really low and rough, and if it stays running, the rpms will drop down slowly and the engine will stall. After that it's hard to start it back up, I think pumping the gas a little bit helps to restart. Also, the throttle response is very delayed.

Other times it starts right up and runs fine, although sometimes the idle seems a tad high as well

Any ideas?

Try taking the throttle body off and remove the IAC from it's housing. Use a old toothbrush and throttle body cleaner and clean as much carbon build up as you can. Don't for get to clean the IAC passages to the throttle body. Make sure on the IAC that the tip of the pintle is no further than 1/8" from the flange or damage can occur.

Do you hear any hissing noises or does the idle fluctuate?
How old are the injectors and do you have a fuel pressure gauge and ohm meter?

OH, what year model are we talking about? 1992?

the 92 and newer IACs are not adjustable.

It does sound like the IAC is failing. I would also check the harness. I have found that the plastic connector is prone to breaking and creating very bad connections. Check that.

Quote:I never knew that any IACs were adjustable. How does that work?

To the OP, It wouldn't hurt to check that the ECT sensor is working consistently.

RACE ON!!!

Horsepower,

Does yours sometime take a bit of time to crank? I am having a very similar problem. The problem is intermittent like yours.

I am not trying to hijack your thread, but figured it was best to keep my problem in your thread since the problems are similar.

My car on it's first start of the day is hit or miss. Sometimes I will let it crank for 4-5 seconds and it will start right at the end. It might go into a fast idle or get very rough and the idle will go way down or stop all together.

The stopping all together seems happen more (now) if the car is warm and I have let it sit for 10 minutes or more. The "Service Engine Soon" ligh has come on but there are no actual codes thrown when I check it.

I will check my throttle body. My 88 4+3 only has 40k on it and the last owner only put 12,000 on it since 1999.

Does this sound like the throttle body to you gurus? Thanks for the help.

Keith

Does it do this only on warm restarts? Or just randomly? If it's on warm restarts your injectors are likely flooding the intake after shutdown and causing the rough idle. A stuck egr can also cause erratic idle. What year is your car?

Its a 92 CentralCoaster.

No IACs i know of used on Corvettes are adjustable, id say youre thinking of the TPS, which was last adjustable in 1989 so im led to believe.

Had a similar problem -- turned out to be a weak battery. After sitting more than a couple of days, the voltage dropped low enough that fter the car started, it coughed and sputtered and did not want to run. Replaced the car battery and the problem went away.

Quote:

Thanks for all the responses guys. Way more than I got on that "other board"

I don't think it the battery because I drive mine everyday and it's never been low I don't think.