2008 Mini Cooper S Exhaust covered in black soot

CRIMSON GHOST

MEMBER
2008 MINI COOPER S
4 CYL
FWD
MANUAL
10,000 MILES

2008 mini cooper S, JCW convertible. 10,000(ish) miles.

I replaced the stock cold air intake with an aftermarket version about 3 months back – no issues. I then replaced the stock exhaust with a more open 2.5" sport exhaust. I now have a fair amount of black soot on my tailpipes. Does this mean the vehicle is now running rich and wasting gas? How do I correct this without changing the exhaust back to the stock design? I know many people that have put this very setup on their Mini Coopers and have not experienced this problem – well, is it a problem? Could it be something else and simply be coincidental that its occurring shortly after I installed the new exhaust (about 3 weeks back).

3 Replies

JAMES W.

MECHANIC
2,394 POSTS

Cute little car. My first experience with a "Mini" was many years ago and wondering how they could crank so many horses out of a motor you could carry under your arm. First thought, being you just changed the exhaust, you may be paying a little more attention to your tail pipe than you did before. Also, with the larger output, the carbon in and around the pipe would be more noticeable. Fuel consumption? Keeping in mind you may be pushing it a little harder, has it dropped considerably, or does it appear to be idling or running rich?

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Thursday, October 9th, 2008 AT 5:53 PM

CRIMSON GHOST

MEMBER
2 POSTS

Hi James,

I think you are spot on. The new sport exhaust sounds very aggressive and I concentrated on my driving today (after posting on this forum). I stopped at a car wash and washed it all up - when I got home, approx. 40 miles post washing, the tip's were clean ! I also did not "get on" it.

The stock cold air intake had a flap that opened at heavy acceleration (4K rpm) Once I removed that stock box with a true cold air intake the supercharger whine plus the sport exhaust sounds sweet ! I have been racing the gears on a few occasions and taking it to red line through 4 of the 6 gears and pushing some of the top end. After riding home today under normal driving conditions and not having any soot I think I was able to answer my own inquiry.

I will continue to monitor the situation and report back if I notice anything definitive. Thank you for being here !

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Thursday, October 9th, 2008 AT 6:09 PM

JAMES W.