Soot on rear bumper and garage floor, with test pipes, normal?

[bmwm3s65]

I started noticing soot on the garage floor and on the bumper after each drive about 8 months ago. I had a tune, test pipes and megan racing axleback. 4 months ago I spun a rod and replaced the engine with a reman from bmw. the new engine is on stock 241e firmware(no tune) with test pipes and megan axleback exhaust. I still get soot on the bumper and floor. coils were swapped from old engine. spark plugs, o2 sensors, low pressure fuel sensor, fuel breather valve and injectors are new. has anyone else experienced this with a similar setup? Its bad enough where I can wash the car, go for a 2 minute drive around the block and then see what looks like dust/soot all over the back of the car. I don't remember this happening the whole time. I had the same setup for over a year before i started noticing it. I tried different gas stations. I always fill up with 93 from shell currently. My car is lemanns blue and I can easily notice it. My main concern is that it seems to be running rich, due to the amount of soot I am noticing, which i am wondering could have been caused by coils and I am afraid that is what killed my old engine. If it could possibly be the coils I want to replace them. Other than the soot, i do not have any backfires, engine seems to be running good and smooth, same as the old engine before it spun a rod.

[Davisca455]

Originally Posted by bmwm3s65

I started noticing soot on the garage floor and on the bumper after each drive about 8 months ago. I had a tune, test pipes and megan racing axleback. 4 months ago I spun a rod and replaced the engine with a reman from bmw. the new engine is on stock 241e firmware(no tune) with test pipes and megan axleback exhaust. I still get soot on the bumper and floor. coils were swapped from old engine. spark plugs, o2 sensors, low pressure fuel sensor, fuel breather valve and injectors are new. has anyone else experienced this with a similar setup? Its bad enough where I can wash the car, go for a 2 minute drive around the block and then see what looks like dust/soot all over the back of the car. I don't remember this happening the whole time. I had the same setup for over a year before i started noticing it. I tried different gas stations. I always fill up with 93 from shell currently. My car is lemanns blue and I can easily notice it. My main concern is that it seems to be running rich, due to the amount of soot I am noticing, which i am wondering could have been caused by coils and I am afraid that is what killed my old engine. If it could possibly be the coils I want to replace them. Other than the soot, i do not have any backfires, engine seems to be running good and smooth, same as the old engine before it spun a rod.

Full Akrapovic and a supercharger for me.
First picture is of the exhaust around town, it looks slobbering rich to me.
The second picture was taken at the track.

My rear bumper gets dusty immediately (less than 2 miles) after a wash, but I couldn't definitively say it is all exhaust.

[bmwm3s65]

Thanks for the reply. that looks similar to what I see, however, I would think that it is mostly from the exhaust because I do not see it anywhere else on the car, only the back of the car and mostly the bumper, tail pipes, Etc. I was thinking of getting BMW logger or inpa or something and pulling the AFR, however I do not know what is normal and what is out of range. It maybe something a tuner could help me decipher.

[Davisca455]

For my car, I actually thought it was just dirty dusty stuff from the road billowing up behind the car and landing on the horizontal parts of the rear of the car?

[astris]

Back of my car looks like it's been through a dust storm after long drives. Test pipes and supercharged.

It would get dirty like that when stock, just not a quickly.

[Davisca455]

With primary cats deleted, I guess it wouldn't surprise me if there is increased soot.

[DukeofAlexandria]

When I first purchased my vehicle, I noticed that these cars have horrible backdraft and wake dynamics on the tail end. I haven't seen a fluid dynamics chart (just because I haven't looked one up, but I'm sure they exist) but after owning mine for many years and trying multiple exhausts, it's just the nature of the aero dynamics and our wake profile.

Carry a bottle of your favorite shine spray and a new rag after long trips, only way I've found to combat it thus far, sorry!

-Duke

[Drv4fun]

I have had mine since new, first thing I noticed after the drive home from the dealer.