Hi All -

If you own an m104 engined vehicle, your time will come to troubleshoot it. My day is here. My wife drives an exceptionally clean 1993 300E (124.028) with the 2.8 liter m104 engine (104.942).

It had been having the oh-so-common misfire problem, so I finally got around to changing out the plugs, coil connecters, and wires. Proper Bosch plugs used, ignition parts were Bosch wires and Beru connecters. Engine is now smooth as silk again. This leads us to stupid question #1. The valley housing the coils/plugs/wires on the m104 has a cover held in place by six allen head bolts. When I put it all back together, I cannot get any one of the bolts started - it's as if they are too short to reach the threads - they just spin. The cover is sitting a few millimeters above the valve cover gasket. I'm open to suggestions. Not an urgent problem, but I'm sure the engine will be much happier in wet weather if the ignition system remains dry.

Moving on. The engine now has a wandering idle and occasional hesitation at low RPM/part throttle operation. I'm going to pull the codes using Arthur's reader, which leads us to question #2. I know where the 16-pin diagnostic connector is located, but into which slots do I plug the three banana plugs on the code reader? I've scanned through about a million m104 posts and everybody is reading codes like crazy, but I've never seen a description of how to use the code reader?

This car had the wiring harness replaced under Starmark 4-5 years ago, so at least that should be OK.

Thanks in advance for any help,

- JimY