Is this normal

[tmkassin]

Today I removed my throttle body and cleaned it. Idles much smoother now. It still seem to idle too high to me, about 850 rpm's. Also when stopping it idles at about 1200 rpm's until coming to a complete stop. Stick shift. Is this normal?

 

[Hib Halverson]

No, it's not.

First, I'd look for a vacuum leak. Perhaps the TB gasket "slipped" or the TB itself got warped. Or, maybe a hose has come off somewhere.

Then, I'd check the minimum air adjustment to make sure it hasn't been inadvertantly changed. Next I'd reset the IAC. Finally, I'd adjust the TPS per the FSM.

 

[tmkassin]

Thanks for the reply Hib. All the vacuum hoses check good. New gaskets in the throttle body. There was a leak at the booster for the power brakes but that was fixed last week. Is it possible that the IAC is not functioning properly without showing a code?

 

[vetteoz]

All the vacuum hoses check good. New gaskets in the throttle body. There was a leak at the booster for the power brakes but that was fixed last week. Is it possible that the IAC is not functioning properly without showing a code?

Any play in the butterfly shafts? They wear out of round and can butterflies can hang up on the bore unless the throttle is tapped to close fully
Don't believe there are any codes for IAC on 92

Obviously you can't adjust your TPS but can do IAC
Corvette Action Center Knowledgebase :: 1985 - 1991: Technical Article: How to Adjust your Early C4 TPS and Idle Speed

 

[tmkassin]

Butterfly shaft is good, no binding and no wobble. Tried the starting fluid method of looking for any vacuum leaks and all checks good. Today I am installing a new IAC. Can't figure out anything else it could be.:confused