slik98z

i gotta 98 z28 with ~45k miles on it now. when i got the car at 38k miles, the idle seemed a bit high but i got such a smoking deal on it i didnt worry about it. Now its time to get around to it. heres whats going on...
When i start the car it fires up great, runs strong, the rpms stay at 1100 for a moment, then drop down to ~900-950 rpms and just stay there steady. I have a m6. if im not mistaken i should be around 750-800 rpms without the a/c on, and around 800 with the a/c on? when i turn on the a/c it doesnt change the rpms much. maybe 100-200 rpms. I haven't changed anything, but i did have the a/c system checked for leaks and it was A-OK.

i was thinking about changing the IAC but i thought that would make my idle more rough, bouncing it around a bit more. Any ideas? I live in nothern Va, the car came from Colorado...could there we a different factory tune for a car that went to a higher altitude (the lady lived about 4600 feet above sea level compared tomy 250 feet above sea level) just trying to trouble shoot thats all.
Thanks in advance guys
Travis

wrencher

iTrader: (2)

First thing to look for a vacuum leak.
The IAC could be sticky also.
Do you have a tool to scan the PCM with & confirm the idle speed , commanded IAC counts etc?