can sombody help me. my idle goes up and down alot. like even when the car is warmed up and i stop at a stop light, my rpm's would go up to like 2k then back down again, and sometimes go even lower and chokes, and once in awhile it would even shut off cuz it goes too low. can somebody please help me? could it be the spark plugs? it is even worst when my car is cold. sometimes its hard to stop. i just got a new tranny, could that be the problem? i don't know what to do.

vinh766

(97 Eclipse GS)

Go get an 8mm socket and pull out your IAC motor. See if it's full of carbon and clean it real good with some carb cleaner. Also see if you can switch TPS sensors with a working one and see if you prob goes away. Are you Auto or 5 sp?

any CEL's? thats where you need to start. you might have a bad IAC like i had or maybe a vac leak

Yeah when I installed my new motor, I had the same symptoms you have. I changed my IAC sensoe and all is better now. Give that a try. Good luck!

Just in case you don't know how the IAC sensor looks like, in green. The pic is a drivers side view of the TB.

thank you guys, but what exactly is an IAC anyways. thank you so much though.

oh yeah, my car is a five speed, and when im breaking my rpm will go up to 2500 until i completely stop, do you guys know what that could be? can you please tell me what those sensors and stuff mean? like IAC and STP or watever please, im new at this. thank you. and by the way, i love all ur cars and im so jealous, i will try to post my car's pix up soon too. thank you

Clay had a pic of it in a post ^^^. It's behind the Throttle body(TB). It has 2 8mm bolts and it comes out. IAC is Idle Air Controller. Sometimes won't trip a CEL(check engine light) but will mess with your idle. Could also be your TPS(throttle positioning sensor). Both are about 60-70 bux each from Autozone. I would clean the IAC first.

People are misleadingly calling it a sensor, it isn't. It's more of a valve. It IAC = Idle Air Control Motor, the motor portion pushes a plunger in and out sealing and openign an extra path for air to enter the intake manifold controlling idle up or down depending on the engines air needs at idle.



15.9 @ 86.7mph

Injen CAI, 55mm TB, P&P Intake, Crower Cams, Hooker Header, ERT/Catco Cat, GS-T Muffler, AFX UDP, Crane Ign Amp, S-AFC

Correct ^. Sorry about the misleading info dude.

thank you so much guys, the IAC was the answer, it doesn't idle weird anymore, but the car still doens't start as crisps as it did b4. like its still choking for more. can you help me out on that? please. thank

Check your spark plug wires or spark plugs.

Don't underestimate a battery on the way out too, that will cause longer starts. Plugs and wires is a good place to start, also fuel filter if it's more than 30k old.



15.9 @ 86.7mph

Injen CAI, 55mm TB, P&P Intake, Crower Cams, Hooker Header, ERT/Catco Cat, GS-T Muffler, AFX UDP, Crane Ign Amp, S-AFC