1993 300E M104 Backfire
We have a 93 300E with the M104 engine. It backfires on startup. It is violent enough that it blew the big hoses off where the upper and lower intakes meet. It is very intermittant, but it does happen. It seems to me to do it more on hot soak, but that may be irrelivant. When this happens, it seems to backfire the moment the engine starts to crank. We have checked cam timing and have watched the crank sensor with a scope while cranking. We have not had it backfire with the scope hooked up. The crank sensor reads correct when cranking. The cam sensor seems ok as well.
Mercedes Benz Master Tech
ASE Master Technician
Owner of "Behind the Star Inc."