Do you guys have alot of black build up on your exhaust tips? My xB is about to hit 10,000 miles, it should not be running rich with no mods except a axelback right? I've noticed it on a couple other xBs and small import cars, but my 01 chevy malibu does not have any black around the exhaust tip whats the deal? This came to mind, I use E10 ethonal (in both cars) but it burns cleaner than strait oil it should not make a differance right? What are you thoughts, thanks for the help.

 

I have to clean my exhaust tip daily to keep it from turning black and staying black. Not sure why though

 

mine only has 7000 miles and the xb's do run rich and mine has that on the exaust. just use some wheel cleaner on it and it will take it off

 

It’s easy to clean off with just about anything, I think the main question is what causes it

 

from what i have read here on sl that the cars run rich to keep the temp down and that is what causes this build up

 

The engine management system produces the most efficient fuel/air mixture for the driving conditions at any moment, and the thermostat controls the engine temperature.

 

My exhaust tip turns black too...I hope someone can answer your question

 

Not always true, I've seen brand new cars run in the low 9's on an innovate wideband AFR, for example the new Mazdaspeed 6 puts down around 9.6, very rich for a piston engine.

Running rich can increase engine life, run cooler, etc. as mentioned above. Alot of cars come rich from the factory. In fact, most turbo cars are very rich, hence why you can turn up boost in alot of those without running into detonation issues. You add air and move the AFR's into the correct range...

out

 

I have the same '06 TCM xB, with a Valor exhaust tip. The Valor has a wide flat rear-facing internal area to display any black deposits. But there isn't anything black on the tip or inside the pipe. I wonder if black deposits come from the engine or are could be dirt.