2000 3800Sc from GP, (still has All stock components, EGR and such). starts right up idles a little high initially, then after about a min, it drops to about 900. thenafter about 2 minutes, the idle will start to rise again, to about 12-1400 RPM. any ideas ? no vacuum leaks. thanks
Did someone tune that PCM for you, or is it straight out of the wrecking yard? Sometimes from the wreckers you get something that has a weird tune in it already.
It sounds like the idle goes high right around when closed loop kicks in.
Usually a high idle when going into closed loop is something not accounted for in the tune causing it to run poorly.
Examples that can cause it:
Air leak after the MAF (would have to be pretty significant for an idle that high). IAC issue Bad/failing Injector(s)
Those are the main ones I can think of. Other than a messed up tune/PCM that can really cause issues.
