Ok ive read a lot about this in many forums around this site and others for that matter, and have yet to find my answer so i figured id start my own. I have a 2001 s2000 with an 04 motor and ecu. The rpms, when coming to stops, intersections or even just barely tapping the gas once its warmed up, will drop so low that the car will start to shake and even sometimes stall. the car idles at about 6-700 rpms once warm, i dont have a manual and im not sure what they are supposed to idle at, and i dont want to go messing with my idle if its not whats wrong. when i got the car, i was told it was the iac valve. which i took apart and cleaned and it made no difference (would rather not buy one if its not the problem) seems like if i let the car warm up for 2-3 minutes, and drive it, it runs like a champ with the rpms a little higher (which made me think maybe i did have to adjust the idle). any help would be greatly appreciated. its driving me insane.

 

I have a similiar issue with mine and have been talking to peeps and trying things and so far have had no luck. I have replaced the spark plugs, did the MAP whack and cleaned it, cleaned the TB, Cleaned teh IAC, ran fuel additive, compression check, leakdown test and still no luck

The problem is not always there either which is making it harder to diagnose. If I drive the car for a long period of time the idle gets smoother, but if I turn it on when its cold and drive short distances (ie les than 20min of driving or so) it stumbles. It used to stall from time to time but hasn't done it in a while [knock on wood].

If I cant figure it out soon I will put the car back to stock and take it to a dealer

Good Luck!

 

I thought I was the only with idle issues.

 

You are the only one with lots of issues, but we both have idle issues

 

just letting you guys know, i played with the "throttle stopper" that locking nut with the allen key screw, just adjusted it 2 threads higher, car still idles around 700rpms, but no more drop, well it does slightly, but nowhere near enough to shake or stall the car, car runs great so id recommend checking that if youre having problems.

 

I've already adjusted it. Thanks though, and I hope yours stays running better

 

car runs great except for when i let the car idle for more than about 10 minutes, its starts to run rough, almost like the rpms are raising and dropping, but not enough to even register on the tach, just a slight putter out of the exhaust. a little annoyting but what could it be?

 

Where is this throttle stopper?

 

Either of you guys try this? Idle Learn Procedure

 

Cable It's the adjustment nuts on the cable that goes to the TB.