Curt

Hello again, I have a slight problem with my idle. Just the other day I noticed that after the car is warm, and when sitting at a stop light idleing, it idles at about 1100 or 1200 rpm. Thats way too high for my manual that is supposed to idle at 850. Now in the past the car has idled perfect but this is a new problem.

While stopped at a stop light and the car in gear I am able to hold the brake and slowly let the clutch out which brings the idle down to 850. I can then push the clutch back in or put the car in nuetral and it remain at 850 and then slowly start to work back up to 1000 rpm. Sometimes it will remain at 850.

Now I know I can just turn the idle screw to adjust the idle speed but I dont think that is the problem because it has been fine for a long time. One thing I will check is my timing. It is possible that my timing has moved or something but if it had I dont think that it would idle at 850 some of the time. The timing belt is new and retentioned about two months ago. but I will check the timing and see where it sits.

Does this sound like it could be a flappy valve issue? or has anyone come across this same problem?

Rich9928p

Curt,

Your '79 doesn't have a "flappy valve", only S4s and newer 928s have the dual resonant intake system.

Your problem is probably caused by a vacuum leak which also increases the idle speed. You don't want this condition to remain because it also leans out the air-fuel mixture. So check for leaks in all the lines.

One other possibility is the throttle cable is binding. Check the linkage at the throttle body and where the cable comes through the fire wall.

Curt

Thanks Rich, a vacuum leak does sound about right. I was thinking that the flappy valve was the big flap that pushes down just below where the round part of the air cleaner attaches to the intake system under the spider.

Sorry I must have my terminology wrong.