This is hard to explain, but sometimes idling my 99 v6 will start like misfiring/backfiring and idle will flucate a bit. On the highway at like 40-50+ if i coast in neutral/clucth in the rpm will flucate from 900 to 500 and sometimes the car will even shut off but if i roll with the clutch out in gear and the rpm up it everythings fine. Also i find that at lower rpm like 1000-3500 or so i find the car isnt responsive like it should be almost like it takes a second or so for the engine to get its fuel but at higher rpm it seems fine. I am just wondering what could be a cause for this? Sorry, i am no good at explaining things.
i was having an issue with that for a little while. tried cleaning the MAF, it didnt help. finally a CEL popped up, p0171 & p0174. the codes would come and go intermittently. pulled off my IAC and bench tested it, found out that it would sometimes stick wide open because it was full of carbon deposits. so i cleaned it out real good with some brake clean and let it sit for a while to dry, then put it back together. the result was a perfect idle.
these should to be cleaned regurlarly every 30k miles or so once you start getting higher miles on your car (around 100k + miles).
symptoms of a dirty/sticking IAC include; hard starting, high idle, bouncy idle, no idle at all, and stalling when slowing down/coming to a stop. it can also cause the car to bog down on low-end acceleration. if it starts sticking open a lot, it'll set a CEL indicating a lean condition on both banks.
well anyways, it cleared my idle up almost perfectly.
here's your IAC,
unplug this connector,
and loosen these (2) 10mm bolts.
and be careful with the gasket, dont break it or lose it.
-2000 3.8L TKO600, 1.8 60ft, 8.71 @ 81mph
-1988 Jeep XJ, bone stock 2wd
-1994 Jeep XJ 4wd, 3" lift, 31" tires.. rust in peace..
-1997 Jeep XJ 4wd, 7" lift, 35" tires, front/rear lockers
-Bronze Level Porsche Technician