mjfox

Hi
got a 92 when I start it the idles is high at 1000-1200 rpm and wont settle after driving stays high any ideas.

thanks mike

krackenvette

Do a search for IAC testing and cleaning.

C409

............ Check for vacuum leaks ... brake boosters are notorious .....

loaded vet

I have a 1987 that had the same problem a couple years ago. After fiddling around with the factory weather pack connector not making a proper contact, I finally made my own cabling and hand plugged in each wire connector to the stepper motor. Since then I have not had any problems with the engine idling. I don't know if there is a design problem but both the factory four connector and a new replacement connector were unable to get the male and female connectors to fully engage. Once engaged they simply do not fall apart. Hopefully this will be helpful.

GWN

Cliff Harris

1000 - 1200 RPM at startup is normal. Not coming down is not. Check your CTS (Coolant Temperature Sensor) on the front of the intake manifold.

The ECM will keep the idle high if it thinks the engine is cold. Check for error codes:

http://corvettephotographs.com/c4vettes/codes.htm
http://forums.corvetteforum.com/1576116036-post35.html

krackenvette

Guys, check your IAC. It controls the idle. When it gets old it breaks and doesnt control the air coming in the intake. Its a controlled vacuum leak. You will not get a code, its the only code GM left off the table. And, with a scanner it will show you what the ecm is telling the IAC to do.
Its simple guys.

gravyhound

I would just spend the $100 and get a new one before I would try to clean it, its kinda like that old saying (there is nothing like the feel of a pair of brand new socks.) lol

krackenvette

Rockauto has them pretty reasonable. But, I feel people should learn to troubleshoot prior to throwing money at a car.

raiderz

Could very well be the 2 sensors mentioned above.....or

I had a very similar issue on my 86...was idling slightly higher than that..about 1600 i think, and it turned out to be the TPS ..Throttle Position Sensor not functioning properly...finally got to the point where it threw a code 22 after a few days of high idle...changed the sensor and good to go.

krackenvette

IAC, common issue. NO codes.
CTS= Code
TPS=Code
I am done. Good luck.