DME trouble?
 

Do DME relay's go bad? My 1990 911 shuts off when I stop at red lights, stop signs, etc.? The guy that had the car before me changed the DME, O2 oxygen sensor, set fuel mix, and replaced the idle speed control valve. It is still doing the same thing. Any suggestions.

If the DME is shot I don´t think your car would start at all.

Head temp sensor ??

The car starts and runs fine until I come to a stop. It is especially frustrating when I slow down (coming down a hill or mountain) and the engine shuts off.

Idle switch possibly. Check this thread over on Rennlist: http://forums.rennlist.com/rennforums/showthread.php?t=224986&highlight=idle+switch

Post your findings...
Good luck.

Yes, DME relays go bad and its a common problem. If you still have the original DME, you are due for a failure. The problems you describe could very well be caused by a bad relay. When they die, they act intermittently versus a sudden and absolute death.

It was changed out last year. Is is possible that it is out again?

That would be very unusual. I'd probably start looking elsewhere for the problem. My 968 had a similar problem and it was certainly electrical in nature, it may have been the DME itself and not the relay. I'll check the invoice (dealer fixed it) and see what it says.

In the meantime, check all the connections in and out of the DME box and make sure they are clean and tight. Corrosion is another possible cause of the symptoms you describe.

DME could very well go bad in a year's time. It's a low cost replacement and replacing it will eliminate it as a fault variable.

Change your plug wires. I had an Audi 4000 withthe same problem.
Lots of arching, visible at night only, nothing in the day, that was causing the cars electrical system to shut off similar to yours.
Maybe watch it run in the pitch dark night.

Check to see if the idle control unit is being switched on when the throttle is closed.

With the engine stopped, open the throttle a little by hand and you should hear the switch. Verify operation at the connection to the Idle Speed Control.

For starters, increase the idle speed by turning the control screw on the front middle of the throttle body'