betiller

sent my speedometer and fuel gauges to north holllywood (great work btw). disconnected battery before removing and entire time they were out of car. re-installed, connected battery and started car and now check engine light (CEL) comes on and idle is bouncing. Here is the weird part...I went back to engine compartment and "blipped" the engine using the gray/black cruise control cam thingy and the idle returned to normal and the CEL went out. Awesome! but wait there's more. This happens every time after i shut off the car. blipping the engine with the gas pedal does NOT cure the problem. I have to get out and manually do it with the cruise thingy. WHATS the DEAL? Please help!!!

justin-in-athens

It sounds like your idle microswitch is not being engaged when the throttle (accelerator pedal) is at rest. This will cause eactly the symptoms you describe.

Make sure your carpets are letting the pedal return fully is the first thing you should check.

There are several ways to adjust how the mircoswitch is actuated. You can hear it click with the car off and the linkage returns fully home.

betiller

thanks. I will check it this evening.

betiller

well thanks, but that aint the problem. carpets not fouling return of pedal. CEL on and hunting idle agin. it clears again with a blip of the cruise control "cam". somebody? anybody? please help.

justin-in-athens

I am almost certain the idle microswitch is not being actuated. The cruise control linkage is simply allowing you to blip the throttle in the engine bay and removing the the rest of the throttle linkage from the equation. It may be that you have an ever-so-slight binding of the linkage not allowing it to return fully home when your gas pedal is released. If this switch is not engaged, the engine idle will hunt and you will get a CEL as you describe. Where about are you located?...maybe I could have a look?

JasonAndreas

What CEL code is the ECU throwing?

betiller

thanks for the replies. I am in Macon, Ga. I dont know what code the ECU is spitting out. Wish I did. I listened carefully and cannot detect a "click" when the gas pedal returns to its top position. Should my 53 year old ears be able to hear it? BTW, this is my 6th Porsche, and I currently own a '87 930 as well, so I don't mind turning wrenches and getting dirty, I just need some help figuring out what to do. I have been lurking around this site for a long time and enjoy it very much. A trip to Athens would be a fun little drive.

justin-in-athens

PM me with your email address, I am going to email you a short video.

Flea18

Have you had the car re-adapted with the Hammer or other device since reconnecting the battery?

Sorting out an idle issue myself. With the engine off, I pull backwards on the throttle assembly (slightly) and hear the idle microswitch click. For the crowd, would that indicate that the microswitch is not being activated when I release the pedal?

betiller

thanks for the excellent video Justin! you went to a lot of trouble and thank you. I will work on it tonite. Owe you lunch at the Varsity.

justin-in-athens

Yes, sounds like you have the "same" problem as Mr. Tiller.

Bryan, I hope the video was of some use to you. I will post it here for everyone else---please excuse my southern accent.

964 idle microswitch location video

JasonAndreas