No throttle response, need advice
 

I've been reading the board for a few months, but have never posted before today. I need some help in diagnosing an engine problem on an early 85 944. On start-up, the engine will initially respond to throttle input, but after approximately 45 seconds I lose throttle input. Engine rpm's drop to 800 and are limited to 1200. The engine will not exceed 1200 rpm's. If I try to give it any throttle it drops back down to 800 rpm and revs back to 1200. It does that weird sort of brrr-ugggh, brrr-ugggh idle that jumps between 800 to 1200. I've replaced the air intake boot and all my vacuum lines are okay. Any suggestions on what is causing the problem? FYI: it usually does this for 5 to 6 minutes, then runs okay until I turn the 944 off. Then on next start-up, the process begins again. Several times while driving, the engine cut out on me and behaved as mentioned. On those occasions I had to limp the car home. Please help.

Could be the DME/Fuel pump relay.

Your throttle position sensor is bad (TPS). Mine did the same thing when it went bad. When it goes bad, the DME doesn't get the signal that tells it you have opened the throttle. This means that the DME will only provides enough fuel for idle. You can check it with a VOM or just listen for a click when you open the throttle butterfly manually with the engine off. No click and it's junk.

Later,
Rob

I'm with RobM951, it is probably the TPS. In some cases, adjustment of it can fix the problem. Loosen the screws holding it and turn it slightly so you can hear the "click" when closing the throttle. If it doesn't help, replace it.

/Magnus

hmm,

has the car ever sat in one spot for a long time? it sounds like it could be related to your fuel injection, but i'd first check the electrical connections to the throttle position sensor besides the sensor itself.

remember, the wires in there are 16 years old. a lot can happen to ground wires in that time.

good luck!

obin

yep it is probably the throttle position sensor(TPS). Mine got a lot of moisture in it and the car did the same thing, i replaced it and all was good.