300TE (M104) Sudden Engine Cutout
 

All,

Our 1993 (M104)engine has begun to suddenly die, under a variety of conditions. Symptoms are: 1. ASR light illuminates and tach goes to zero. 2. After the car slows down, all warning lights on the dash illuminate, and oil PSI goes to zero (i.e., the engine speed has dropped). 3. Car can not be immediately restarted, but can always be restarted after waiting 5 to 7 minutes.

This has occurred at steady-state cruising, moderate acceleration, at idle and while decelerating. It has occurred with the A/C both off and on and with the radio off and on. It has occurred on very smooth roads (and at least once, at a full stop).

The Over Voltage Protection Relay was replaced a year ago. The electronic throttle (ASR) was also replaced about a year ago. The car has just come off a major service and the motor runs great, when running. (Problem surfaced prior to the major service).

This will be difficult to troubleshoot, as it occurs intermittantly -- sometimes hours apart; sometimes minutes.

I am, for the moment, ruling out fuel delivery, as the tach goes to zero the instant the ASR light comes on (and power ceases).

Any known weak components in the electronic ignition system (HFM-SFI)? Ideas for troubleshooting?

Thanks,

Alan

<<Any known weak components >>

Had any wire harness insulation problems??

Also, check the fuse spades for a good connection on OVP

300TE (M104) Sudden Engine Cutout
 

I have not had any problems with engine harness. Nature of the problem has me thinking it's an electronic component that is failing when it gets hot, then works after it cools a bit. I'd expect that an engine harness issue would cause erratic restarting issues. This one is a straight "wait five minutes" scenario.

I will check the OVP spade connectors.

Thanks,
Alan

Power distribution is OVP indicator, so you may want to give it a few Taps next time it will not start [ even though it is fairly new]
I would also check the codes at the diagnostic box. There should be codes .....