Idle Surge with A/C

[shane rimmer]

I recently purchased a 2001 ZX2, and, while it runs fine, the idle bounces from 800 to 1300 RPM when the AC clutch engages and then drops back to 800 RPM when it disengages. I found a vacuum leak in one of the elbows of the PCV hose and corrected that after getting the car, but this issue persists. Is this just how these cars work?

[tre2000zx2]

our cars are notorius for idle issues .. just to be sure .. doulble check ALL vac lines including UNDER the intake manifold.. clean the throttle body, IAC, basic tuneup also sct helps idle issues alot as some ecu codes or more prone to having issues at idle, at the VERY LEAST doing the above steps will help your fuel milage. Then you'll just have to deal with the vibration issues. Also our system energizes the compressor clutch in all but 1 or MAYBE 2 possitions .. vent and one other position POSSIBLY ...

[mechtech]

tre has good advice.
In addition to the vacuum lines, the intake has to have no leaks at all.
You could try cleaning your throttle body bore and plate with a rag and solvent, also.

[tre2000zx2]

tre has good advice.
In addition to the vacuum lines, the intake has to have no leaks at all.
You could try cleaning your throttle body bore and plate with a rag and solvent, also.

old toothbrush comes in REALLY handy for that.. just go in short spurts if you use t/b cleaner to it from pooling to much in the bottom of the intake runners. also try to clean the bypass passage while your at it.. just use the nozzle extention tube and give it a squirt.

[iceracer]

The AC cycles causing a change in idle. Normally the IAC tales care of the problem, it may need cleaning.

[Beodude123]

I rarely use the AC, and my idle bounces all over the place. Could be the stereo equipment in the back though....

But yeah, idle on these cars is pretty unpredictable. Unless you have a custom tune holding it at a certain RPM, it is going to bounce.

[shane rimmer]

Thanks for the replies. I will be working to implement most of the good advise given.

[shane rimmer]

Oddly enough, I have been driving the car for the past couple of days, and the issue seems to be mostly resolved. The idle now only varies by about 200 RPM as the compressor cycles on and off. I've changed nothing, so, while happy it's doing better, I am a bit worried that the issue may resurface.

I am guessing it is the IAC mentioned early on. The car sat for a while before I bought it, so is it possible things just needed to get worked a bit?

[mechtech]

Yes.