Originally Posted by hbofinger

Hi all, I just did a plenum seal job on my 1989 560 SEL. I had my mechanic go over the work, do a smoke test, all is solid and OK. He congratulated me on the job. But the car does not accelerate worth crap. It is beyond his knowledge, he suspects something electronic. The problem started after the transmission was replaced.

What would put a 560 SEL into "limp" mode? He noticed that the spark does not advance as you attempt to accelerate the engine.

Any pointers would be appreciated. There are no vacuum leaks, everthing is tight, and the mixture has been adjusted.