Mustang_Eater

Hello All,

When every I come to a stop light my 1989 Corvette seems to have a idling problem.

The egine seems to make the car feel likes its shaking and then it sounds like that slow rumble right before a car dies BUT then it revs up.... to keep it alive I guess and then about 2 seconds later goes into the feeling again like its going to die....and just repeats until I start going.

I've had plenty of project cars that die at stop signs but I always just increase the idle screw (they were carburated) don't know if there is something like that on this car.

Any ideas? Is there a adjustment to increast the idle? I just replaced the spark plugs.

vettme

Sounds like the idle air control is sticking, or even a vacuum leak. Worth checking into before making any adjustments to mask the problem.

Mustang_Eater

Where is the idle air control? Can I get it to unstick?

Thanks!

floridamale

The IAC is located bottom of TB you can remove it and clean the passageways with TB cleaner, it's the sensor with the 4 wire connector passenger side of TB.
There is a lot of information on here in search on how do clean & adjust it
You also might want to clean your TB while your at it the butterfly can get gumed up and prevent it from working right

Mustang_Eater

Ok guys here is the update.

I replaced the IAC and the old one was very messy, while I had the throttle body off I cleaned it up really good with Carb Cleaner.

Put it all back together and now the idle is much better, instead of going all over the place and down to 500 RPM it stays at 600RPM and is more solid.

HOWEVER, when I am idling I still get that "boom" & rattle feeling that a car makes when it's dying and idle. Then to top it off today I got up to 40mph after stoping at a stop light and after a couple seconds the RPMs dropped down and the accelerator pedal became iresponsive like it lost all air or gas going to the engine. The car did not die though just could not accelerator at all!!!

I pulled the car over, let it sit for a bit put it in park for a bit and then drove away with out any problems....

What am I missing? I am going to adjust the Throttle position sensor a little higher and replace my air filter (air filter isn't bad right now though, not sure how old it is)

What else can I do to get a smooth idle and stop the car from wanting to die on me!! Please help, it is really freaking driving it and being worried it's going to die any second!! I don't think it's a injector because it drives just fine, idle is the problem? And I'm running injector cleaner in the engine the last two gas tank fill ups.

BADDUCK

Injector cleaner isn't a good idea, I understand, if you have the original Multec injectors. Supposedly it harms the windings.

Mustang_Eater

Oh! Great!! I hope I havne't broken one.......

BADDUCK

If it runs better cold than hot you might change out the O2 sensor. It is cheap and easy.

walter schweigert

Have you checked for trouble codes?

Mustang_Eater

It definely runs better hot, it is hard to start cold.

I just went through the whole process of reseting the IAC and it acutally seemed to work. Drove it around and It was steady idle, then I pulled it into my garage and sat there in drive and watched as the idle slowly fell to 600, the to a shake 600 : ( So I am back to square 1

I have not check the trouble codes... I don't have one of those readers to stick into it. I may have a old meter somewhere but not the book to read the code...

Mustang_Eater

Put the code reader on and I just get 12 over and over so I don't see a problem.

When I was following the guide to reset after the IAC I did not stick the paper clip into ground the A & B diagnostic slot.... because at that time I didn't have the code reader available, is that really necessary? Should I do it again and ground it or does it not make that big of a difference.

Really apprciate the help all!!

walter schweigert

I would do it again and follow all the steps necessary to reset the IAC, then check and adjust the baseline idle, then I would check the TPS setting (.54volts).

The procedure is outline very well in a recent thread, some where here.

walter schweigert

See if this link works:

http://www.corvetteactioncenter.com/...and+Idle+Speed