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Ok, so as of Tuesday last week I've now got an idle issue and despite searching the forums I'm not quite sure the cause, so am hoping for some imput and ideas. The Problem What will happen is when I start the car (typically from cold) it will be ok for a minute or so, then anytime I'm in neutral the idle will be hunting, going down as low as 200 and up to around 800, like a pendulum. If I'm driving with higher revs when I get into neutral the drop and swing of revs will be harder and it will be on the verge of stalling. It will eventually close the range of revs until it gets to the 800 idle the car is set at. The longer I drive it the less it will hunt until eventually, say after 10 mins of city driving it will idle normally. Also, using AC or brakes doesn't appear to affect this issue. Some specs R33 GTST bigger turbo, 740cc injector, FMIC, exhaust, Z32 AFM, Walbro fuel pump and a Tune in December. All of these parts were bought and fitted new within the last year. In addition here are some common things to check regarding a poor idle that I've already considered. - AFM poor soldering (unlikely as is a new unit) - Vacuum/ IC piping - checked and were ok, and many have been replaced with silicon anyway - ACC clean - done - Fuel filter - replaced - Plugs - 1 month old - O2 sensor - 9 months old - Coil packs - original, but are in good condition (and I don't think this issue relates to them anyway) - Water temp sensor - original What I think It might be Seeing as my problem seems to be the regulation of air while the throttle body is closed, I'm thinking it could well be part of the Idle Air Control Valve system that is causing this. From what I can see there are two main parts, the popular one that people seem to talk about being the ACC valve. While I have cleaned the IAA unit (That's the wad hanging off the inlet manifold that contains the ACC, the cylinder hanging off the side) has anyone heard of that ACC unit being faulty or failing? Could it be a case of swapping this out? The other suspicion I have is that it might have to do with the Air Regulator, which is the unit located below the IAA unit and connected by a vacuum hose (which continues back into the inlet plenum). According to the manual the air regulator is fully open below 20 degrees, half closed above 20 degrees and fully closed at above 60 degrees of water temp. This would seem to correspond to the times in operation that I will typically have this problem. Has anyone had this unit fail at all, or could it be cleaned back to good health? And aside from this, is there anything that I may have missed which fits the symptoms of my idle problem? Ok, thanks all
