92 500SL blowing black smoke @ idle
 

92 500SL blowing Black smoke heavy @ idle
Hi Everyone,
Have great 92 500SL great condition daily driver, 150,000 miles, well maintained, just one day started blowing heavy black smoke just at idle, this smoke is thick, so far I changed fuel filter ( next to fuel pump ) fuel pressure regulator, several vacuum hoses, nothing seems to change this embarishing problem. Mechanic's do not want to waste time because of year.
This must be a simple problem, it seems it started a little after my transmission maintenance flush.

Thanks for any advice

Two items to check
 

First dose your trans have a vacuum modulator? it might have a small hole in it, but that smoke is normally light in color. The second thing is the fuel mixture have the lamda setting checked, search lamda and X11. sounds like the air fuel ratio is off.

Yes, sounds rich. How is it running? How is the fuel economy?