Has anyone here tested an IAC on these cars? Looking for specific voltage input at idle, off idle, etc
My Grand Prix has decided to randomly rev up to like 2800-3k on startup sometimes. It normally revs up to 1300 or so to get the fuel atomized better when it's cold, then lowers down to idle - but it shoots right up to around 3 grand and won't come down at all when it does this.
In gear with the drag from the trans (holding the car in place with brakes, of course) is around 1400-1500 revs. I had it happen to me when I was out for a drive, around 50km/h downhill where the car is normally idling it was at 1400 RPM. Slip it in to neutral and it shoots up to the aforementioned 3k.
Throttle position has absolutely no effect on it whatsoever. It does all of this with the throttle closed.
I cleaned the bejesus out of the IAC valve when I got the car. No DTCs and no running problems to speak of other than this phantom throttle.
It went away on its own when I was out driving, but the only way to get it to stop prior to that was to kill the ignition and start it again, hoping it has gone away. I pulled the connectors for both IAC and TPS to see if they were dirty but they were okay..blew them out and hooked em back up and it started normally.
I suspect either the TPS or IAC valve, but I didn't get codes for either of them. Either the TPS is telling the computer I've got my foot down, or the IAC thinks it's being told I have my foot down. At least that's my n00b theory.