Black soot on rear bumper

[Maine]

My 2004 Arc has been known to puff black smoke out of the exhaust (I have never seen it, just been told) and now I see black soot above the tailpipe on the rear bumper.

What is the cause for this?

[mike saunders]

Black smoke usually means a rich mixture, which should show up as a CEL.

Sure it's not blue smoke?

[ivanwakeup]

Rich running condition would make the most sense- i had the same problem on one of my other cars a while back with black soot in the tailpipe and on parts of the bumper.

You may or may not be getting a CEL- but to know for sure if its rich, pull the plugs and if the plug looks sooty too i bet you anything you have a rich mix.

[Breau]

My car puffs out black smoke now because I had mine tuned and it does run a bit rich. Don't think turbo smoke would stick to the tail pipe like the black smoke from running rich would. My tail pip is always dirty now.

[Maine]

I have no check engine light on, and no codes stored.

My car is tuned as well, but its always given a puff of smoke when I merge onto the freeway (although I have never seen it, others have).

Guess its just the nature of the beast.

[ivanwakeup]

a tune would make a lot of sense, as many maps will always up the fuel request. So if you're tuned- your probably safe, and i can tell you running rich is MUCH better then running lean

[Breau]

Yea dude, that is going to happen if you have a tune. My friends told me the same thing, that you can see a puff of smoke when I got on the throttle, but we knew it was because it is running rich.