my Idle is crazy!!

[drifter sx]

two weeks ago im sittin at a red light. the car is in neutral, theres no one around, im changhin cd's then suddenly my car revs up to 3000 rpm!! it stays like that for 10 seconds, then drops back down to 2000 rpm. my foot is nowhere near the gas pedal during this. its been like that since. ive changed the air and fuel filters, gave it a tune up but no change. im still idling at 2000 rpm. W-T-F???

[drifter sx]

PS. it used to idly at 1100 rpm, which i believe is normal. its a 90 5spd hatch..

[AmIdYfReAk]

actually, according to what i've read the Normal idle is around 850 +/- not 1100..

i would be checking around the intake and etc to see if you have a vacume leak. ( just listen very carefully for a Hissing like suction sound )

if you do hear it try and track it down and plug with with your hand and it should correct ( if its the problem ) for as long as you have your fingers on the leak.

[onosqv]

At least your car doesn't have the other idle problem (the one that dies).

I've noticed that problem on my car (I have auto tho) when I do a lot of stop and go recently.

Does it start idling @ 2k right from the beginning? or after it starts warming up?

Mine started getting like that in conjuction with the water temp rising - so that may be the problem.

If it's after it starts warming up, I'm thinking it may be a coolant / coolant sensor related problem - of course I'm probably 90% wrong - but it's worth a shot.

Also, there are 2 idle adjustment screws - the one on the ecu and the one in the engine bay.

Hope that helps somewhat.

[AmIdYfReAk]

i wouldent tuch the idle Screws on the ECU, that should be a LAST resort..

if something, even as little as the idle changes then something changed on the engines setup... this shouldent be compensated with something like the ECU unless you are 100% sure what the problem is and what causes it/etc.