Sudden Onset of Misfiring
 

The car is a 1993 300E. Car started fine in 20 degree weather. Somewhat sluggish initially because I am using Mobil 1 15W-50. After letting it idle for a minute, put it into reverse and it died. Restarted with a bad misfire. Drove car to work 3 miles hoping it would sort itself out. It died on the way to work but restarted but is still misfiring badly. Any suggestions on how to diagnose what is wrong? Could it be a coil? Thanks.

This reminds me of my similar issue several years ago. It had to do with the main wiring harness, (common '93 problem) but it was an extended warranty matter. Also I had a coil pack die two weeks ago, just like flipping a switch. This was a perfect constant miss. I replaced the coil pack, problem solved.

I checked the codes and on pin 7 got 13 flashes, on pin 8 got 3, 9, and 11 flashes and on pin 14 got 10 and 14 flashes. If I am reading the codes correctly, these codes are for coolant temperature sensor (pin 7), intake air temperature sensor, O2S (low or high voltage), current too high (pin 8) and engine control module and closed throttle position contact switch (pin 14).

Do you think this points to the wiring harness? I hope not. The car is a 1993 300E with a 3.2 liter 104 engine. Thanks for your help.

My 93 gave me the exact same codes plus a few more when the harness went south. If you are handy, you can rebuild it but if you d, make sure you get a new computer connector from MB. I rebuilt mine and all was well until a shor developed in the connector at the ECU. I am waiting on a new one to get back on the road.

Good Luck