erratic idle
 

I have been restoring the Porsche a little at a time and had the steering wheel off working on the horn problem and while apart cleaning the gages and replacing bulbs. Now my dash lights up nicely. The other thing I done was replace the tie rods on both sides because they had a little slop in them. So I needed to run to the store and thought I would take it and try the new tie rods out and see how it drove, knowing the frontend would be out of align, ( I have struts and bushings to put on before I get it aligned) but see if it helped. I got to the store and noticed that the car would idle at about 800-900 RPM for about 30 sec. and then idle up to about 1000 RPM for about 30 sec. and then back down again. I did not have the heat or A/C on, the temperature out side was about 65 deg. Just kind of strange. I just replaced all the vacuum hoses, I checked them when I returned home and all was well. I don't know what could cause it to idle up and down like that? Any ideas? It also seems to run rich when cold and kind of rough also when cold. I have a new O2 sensor to replace the old one thinking that maybe my cold engine problem, I have also replaced the DME temperature sensor just because I had the intake off replacing the vacuum hoses. Any ideas?

my 83 944 was the same way, i think thats how it was supposed to be because i replaced my 02 sensor, i think its called the shudder problem but maybe thats somthing else.

my car actually would start at about 1000 rpm and go down to 8-900, and then stay there until i would give it some gas or drive away. josh

I just ran it down the road and back, at a light it was doing that again. When I got home I adjusted the idle down to 800 RPM, that stopped it. I reved it up a couple of times and the idle went to 900 RPM and is steady their. I guess it did not like the idle position it was set at, that's all I can figure.
Brian

Your throttle position sensor could be slightly out of adjustment. Put your ear next to it and actuate the throttle (engine off), you should hear a distinct click as the throttle moves off of the stop. You might also check that there is a little play in the throttle cable when at idle. I had mine a little tight once and it would not always go back to idle.

Lou