Date registered: Mar 2010
Vehicle: 1989 560SEC, 1989 560SEL, 1995 E420
Mentioned: 9 Post(s)
Quoted: 576 Post(s)
Bummer! Yes, the flywheel has to be properly keyed to the crankshaft. The crankshaft position sensor reads signals from the rotating flywheel and sends them to the EZL, telling it that the engine is rotating, where tdc is, and to fire up the fuel pumps and to set the ignition/timing, I think. If you have the flywheel in the wrong position, the computer will be confused and the timing could be off.
Take a look around the internet. I THINK I read that you can just back the trans out a little and reposition the flywheel. Not sure about that.