Idle Problems

[aabm]

I have a 2000 boxster S and when the car is warm, the idle becomes instable. In cold it’s all OK, but when goes warming the idle starts be irregular. Can anyone help me?

[gsmiller]

I'm by far no expert so take this with a big grain of salt... but I've asked enough questions lately I thought I'd try an attempt at answering one (especially since I've dealt with a hunting idle recently too).

My understanding is this is most likely one of a couple things:
1) Air intake leak somewhere (meaning air is getting into your engine after the MAF sensor so the ECU isn't mixing in the right amount of fuel).
2) Bad MAF sensor (so the ECU is getting bad readings about how much air is coming in).
3) Dirty throttle body.


I don't know the differences in how the car controls the idle when cold vs. warm, but there are a couple things that helped me:

First, try unplugging the wire to the MAF sensor with the car running and see if the idle keeps hunting. The car will run a little worse but if the idle steadies out it's probably either a bad MAF sensor or an intake leak. You can start by pulling the MAF sensor out and cleaning it with cleaner made specifically for MAF sensors. There are plenty of posts out there on doing this. Another thing that helped me was pulling the throttle body out and the cross tubes that connect the intake manifolds out and cleaning them. My AOS had failed and dumped some oily gunk in my throttle body. Cleaning it out with throttle body cleaner helped a ton. If that doesn't do the trick, you're down the tricky path of troubleshooting an intake leak or buying a new MAF sensor (a couple hundred for the part).

[bklyn]

My 2002 did the same thing, first I would check for any vacuum leaks, mine turned out to be an extremly dirty and gummed up throttle body. Basic to remove and clean with some carb. cleaner I would try that first, there some postings on our forum. I now clean the throttle body everytime I do a complete tune up and can not believe hoe dirty it gets.

[aabm]

gsmiller and bklyn Thanks. I will star to clean de throttle body and after will see.

[aabm]

Just an update, when the AC is turn on and the stronger it is, the less the idle varies.

[bklyn]

I know on some vehicles when the ac clutch is engaged a solinoid will kick in to boost the engines rpm's thus leveling out the idle, I do not know if our vehicles are equipped but that might be the reason why it feels better.