Originally posted by Cap'n Carageous
Why does this car blow soot through the pipes and run lean out of the manifold?
If you remember, i had the exact same problem going on for months with my 300E.
After 17 hours of diagnosing and replacing various parts, the tech replaced the entire fuel distribution system with a used system just like in your case. That did it!
But here's the important part: He had the car standing for 2 days before he could start diagnosing it. He was waiting for a new catalythic converter for it. He told me that a clogged/collapsed cat would cause the engine to run very bad (run rich - low milage), no matter how perfect it is adjusted.
The black smoke you are seeing is the remaining soot in your cat being burned. And as long as it's there the engine will run bad and propably cause more soot in the cat.
My $0.02 is on the cat!