Can't solve idle problem...

[Lucas.B]

Hey guys,

I'm in desperate need of some help...

Cold start - starts up fine, immidiately idle drops very low, bounces back up, does this a couple times. The idle continues to suck until the car has been warm for a while, and still it sits at around 650, has continued to get worse the past week. It's gotten to the point where without my foot on the throttle, it almost stalls.

I've checked for leaks, nothin, cleaned the enitire intake as well as scrubbing the ICV...same crap. Replaced the plugs, doing cap and rotor tomorrow.

I've read it could be the TPS, or maybe O2 sensor, and coolant temp sensor. How do I go about checking if these are fully functional? What do you guys think, any other ideas?

Thanks so much for any input

[BCMike]

I'd be most worried about a blown intake manifold gasket. I've seen those symptoms have this as the cause a couple times. When idling cold stick your head under the bonnet on the PS and listen closely. You'll probably hear a whistling and if you stick your finger down back under the injectors you'll find the one that's leaking by modulating the pitch of the whistle. You can also drop a little motor oil down around each intake-to-head seal and find it that way when the slurping sound starts. Of course there are so many other places a leak could come from but in now aging M20s this is as frequent a site as any when it's not the intake boot.

[Bimmerboy91]

what and where is the TPS?