Ive got a small deposit of what appears to be black soot-like material on the bottom tips of my exhaust. i just noticed it the other day while i was filling up my baby. is this normal, or does it indicate my car is running 'rich' ? i have a WRX with just over 10,000 miles on it, i always use 93 octane, uh... my only mod is a K&N airfilter , well and tinted windows :D , ive had all my service done and the requried intervals, and ive been using a synthetic oil since my first oil change. thanks for any info guys ..


rich

Hi,

I've noticed the same with my WRX (3-weeks old today and 1500 miles).

I assumed it was due to my commute driving (i.e., slow) to and from work.

It washes off easily enough however.

Cheers!
Bradus

Originally posted by Bradus
Hi,

I've noticed the same with my WRX (3-weeks old today and 1500 miles).

I assumed it was due to my commute driving (i.e., slow) to and from work.

It washes off easily enough however.

Cheers!
Bradus

I should add that I use premium fuel (93 octane) as well.

I've had that on every car I've owned, every one of them low emission, modern cars. I think it's normal for most cars.

Ultimately, even ULEV engines (like ours) produce some emissions which contain particles large enough to see when the collect in one spot like that. I also think it's just more noticeable on tail pipes with stainless steel tips.

- Kai

is this normal, or does it indicate my car is running 'rich' ? Well, the answers are "yes" and "yes". It's normal first off, but it does indicate richness. From all available information, the WRX is set from the factory to run quite rich under most conditions, therefore we get the soot on our tailpipes. I haven't heard anyone report problems from this, though a lot of the aftermarket ecu solutions "correct" the problem by changing the fuel maps to run less rich. You can also get closer to the edge in terms of pushing power by optimizing the mixture and running leaner, but again, the closer you get to that edge, the more chance you have of going over it, and that's when bad expensive things start to happen.

I've had it ever since the car was new. Funny thing is whenever I wash the car it magically disappears for a few days:D

Originally posted by FloridaWRX
Ive got a small deposit of what appears to be black soot-like material on the bottom tips of my exhaust. . . is this normal, or does it indicate my car is running 'rich' ?
rich

Yes that's absolutely normal and yes your car is running pretty rich. how's that for an explanation?

Seriously, the WRX is known to run very rich (10.0:1 at times!:eek: as measured by autospeed.com).

The rich running made to protect the engine. Don't sweat it too much.

my 1994 honda civic does the same thing...did it when it was new and it still does it...i think its just some of the crap that does get by the cat converter

not necessarily meaning rich or lean..i think it COULD be an indicator...but id first wonder whether the CAT was doing its job, or if it was faulty...ive seen ppl with cars with tons of black crap all over their bumper area near the exhaust tip...and its because they dont have a cat or theres something wrong with their emission system...

no need to worry on a new car, but if its really bad (i.e. all over the bumper area) then yeah get it checked out.

I was about 10 minutes away from asking this exact question.

This place must be the font of all WRX wisdom. :)