awrfc

I have a 90 Model Year S2 Cab which idles too fast. I have checked and or replaced as much of the system as I can think of, with no luck. The car idles at about 1000-1050 rpm when cold and about 1250-1300 rpm when hot. TPS seems ok and is clicking on/off, aux air valve just replaced with a new unit and fuel regulator also just replaced. Could fuel damper have any effect? Any help or thoughts would be appreciated.

Keith
944S2 Cab

Craig944

Isn't there an 'idle screw'? My dad has fiddled w/ a simple screw to adjust my idle before. Is it the one on top of the Cam? Duno, I'll find out for ya and take a picture tomorrow mourning.

Skip

Idle speed on 944's (and most modern Porsches) is controlled by the DME via various parts of the ignition, intake, and fuel system. Specifically, the idle stabilizer is used to control the air/fuel mixture during closed throttle operations. For early 944's, this is only done during cold idle by the aux air regulator. The effect of physically turning the set screw on these cars will only bypass the throttle position switch, which on later cars will actually cause the idle to cycle between ~800-1200 RPM.

Keith, if you're sure all the mechanical bits are working well (and the TPS is set good), you might look for an intake leak... somewhere after the AFM, or, after the throttle (intake gasket... infact, if you moved the intake up to replace the Idle Stabilizer, you may have a leak at the intake-to-head gasket) BTW, the TPS can click and still not be working properly... unlikely, but possible.

Good Luck!

awrfc

Thanks to both of you for the info. If I do have an air leak in the intake system would this not also cause the car to run at a similar idle speed when cold?

Michael Stephenson

Keith,

Your idle speed when cold is identical to mine - about 1000-1050 rpm.

When mine is warm it idles around 900 rpm.