Since this weekend at LS, I've been having intermittent idle issues. It'll sit down at 100-300 rpm and idle there. I've stalled a couple times on stopping for red lights.

My first thought was that my clutch wasn't fully disengaging even worse than before, but since I let off the brakes without rolling and the idle stays the same regardless of last gear chosen that's not it.

Last time it happened I paid careful attention to the sound. I hear an on-off hissing from the front left of my car, probably that air pump for the emissions system. When it turned on my rpms would jump up a bit to 1k or so, then fall back down when it turned off.

So are the votes for my map sensor?

 

Josh,

Seems like you would've thought of this -- but have you reset the ECU? After my spin on LS, I too had really screwy idling until I reset it. It didn't drop to 100 RPM but it definitely felt a little rumbly.

- Warren

 

hmmm, i'll try that tomorrow.

 

i am having idle problems with my car too, but not that low though,.. when i sit at a stop light, my idle fluctuates from 700-1000 rpm up and down and up and down... i am not sure why, it usually idles at 900 rpm constantly..
i think i am going to reset the ecu this weekend and see if that helps.

 

after an ECU reset I still have the problem. an ideas guys?

 

Give the MAP sensor a few thwacks...?

 

My car is doing the same, a couple of times coming up to a stop light or just completely letting off the throttle my car has stalled. It may have done this 3 or 4 times. Idle dips way down to 1 or 2 bars, then sometimes will correct itself and rough idle at 1K, a little tap on the throttle and it seems to get rid of the roughness.

 

i tried that too, but this is different than previous map sensor goofiness i've experienced.

 

I've had idling problems since about 6 months after I got the car. Through the following I tried tapping the MAP sensor, but did nothing.

The idle symptoms that you describe sound like when my purge valve ?? crapped out. A bit sluggish in the lower RPMs. A tendancy to stall and fluctuating idle RPMs. The check engine light took about 3 months of these symptoms to come on. If you tap the gas lightly and then let go does it drop to about 500 RPM and then recover?

The second time this happened I was pulling a P1519 code (Idle Air Valve). It would idle high until the engine warmed. It would then act like the symptoms above. Bottom line on this one was the ECU crapped out.

I think the ECU was flawed since I got the car. I was just chasing symptoms of the ECU. I never rode in another S, so I didn't know how it was supposed to act. The car now acts like I would imagine it should. It's a completely different car.

 

My ECU was replaced when I bought the car. My car has always had a funky idle/almost stall. Especially in stop and go traffic.