I have 1992 mbz 400e w/213k miles. I recently let a relative give me a tune up.I know not the smartest thing. In the process of changing the the wireset, he messed up the firing order. He was able to get the firing corrected however, once he got it started it was only running on 4 cylinders. The problem is that the car is a v8. When the car was at idle I noticed alot of white smoke coming from the exhaust.I mean alot of white smoke. This was odd because, the car was recently driven from South Carolina w/ no issues at all. Furthermore, my uncle was convinced it was firing on all 8cyl so, he decided to drive the car to burnoff the excess that had built up from trying to start the car with wrong firing order. He didn't get the firing order corrected for about 3 weeks. The smoke stopped when driven on the highway. City driving smoke continued. We ended up finding out that one of the coils were bad. Hence not all 8 cylinders firing. Coil was replaced all 8 starting firing again, still had white smoke. Along w/ the smoke I have black stuff coming out of exhaust as well. The car runs fine, no performance problems, no knocking, no crazy sounds, the car runs as smooth as can be. Can you please tell me what this smoke, and black soot is from?