Rev Fluctuation

[Maddog309]

Hey guys, my s2 r33 is running completely fine after its recent rebuild, just one problem. I've been noticing, when the car is warmed up, if I stop at the lights of pull up in the driveway, the revs will fluctuate, doesn't sound real nice. Could this be anything to worry about, or could it be something small? such as a dirty air idle control valve? any input would be fantastic. Tried looking up previous threads before asking this, and couldn't find any relevant info. Thanks again.

[GTSBoy]

Dirty IAC would be where I'd look. I'd also want to hook it up to a Consult reader and see if the timing was stable or being varied up and down.

[scotty nm35]

From my experience the iac valve tries to target a lower revs, but any small vac leak can stop it hitting that target, which gives you that cyclic idle as it tries again. Even a small hose leaking is enough to cause it.

[Dose Pipe Sutututu]

If stock ECU try unplugging the stock O2 sensor and see if it happens when it's warm again.

[Maddog309]

Running Power FC atm

[Badgaz]

nothing to worry about...just give the aac valve a clean everynow and then...check for vacuum leaks too.

[Bushy]

Yeah my bet is on small air leak.