Throttle Position Sensor
 

Could somebody explain exactly how the operation of the TPS works? Is this a part that can be "cleaned"? I think I have narrowed down my weird engine idle/operation to this part. A vacuum leak would be constant right, not intermittent? And the problem is only with a cold engine, goes away literally as soon as the temp gauge hits the first white line. I thought the ICV could also be suspect, but the ICV isn't in operation with the car in gear right? Today I was in 5th gear and the car was literally driving itself forward, holding steady at 1,600 RPMs, as soon as the coolant warmed up enough, I felt the throttle start acting normally and the engine started braking. Car ran normally again after that. Not looking forward to buying a new TPS, for ~$80, but nowadays that seems like pocket change, lol. At idle, it would do the weird surge from 1,100 RPM up to ~1,700 and drop down, back up, etc. New DME temp sensor helped cold running operation but not this intermittent issue. SmileWavy

Thanks man! Probably a great Time to reseal the throttle body while I'm at it.Next project :)

TPS , Determines engine Fuel/Timing operation
 

:eek:Bad TPS is big trouble:
It allows the DME/ECM to determine which fuel and ignition maps to use while engine is operating. Engine Load Functions (Idle, Part Throttle and Wide open throttle) input from the TPS and engine rpm to determine load are critical in engine control management. Even more critical for the Turbo 944's.
Recommend fixing or replacement. Make sure you get the correct replacement. They are not all the same TPS sensors, for all models and years. Check the PET for your model Year 944 and part number.
Later...

Thanks man! Probably a great Time to reseal the throttle body while I'm at it.Next project :)

Hmm... Is there a chance the sensor is too far gone for repair? Maybe better to just get a brand new unit? I'd be worried about taking it all apart just to not even fix it :-/

re
 

Would a bad TPS causing start stumbles and then a fall over? Now she will not start, fuel spark, she tries to start but nothing.

Idle surge is usually the idle valve. Could be stuck open or closed which could affect your part-throttle driving.

Thanks for your reply Spencer,

So the ICV could affect driving while not at idle after all?
Is it plausible that the ICV was sticking while cold and then working once warmed up? Could I clean it up really well to fix the sticking? SmileWavy

Do you have tach bounce? Proper fuel pressure?

re
 

Fuel, spark are fine. Did the jumper to make sure. Pulled the cover and belt jumped 3 teeth.... SOB!!

Was just hoping