Black soot in exhaust pipes?
 

I've noticed with my car that the exhaust tips always seem to get coated quickly with black soot after washing them. Usually that is a sign that the car is running rich. I've had cars in the past do this but never to this extent.

Even my brand new SOLO kit only took about a day or two for the tips to get coated and lose their shine on the inside. When I picked up my stock exhaust from the shop this morning, I noticed that the inside was absolutely coated from front to back with this crap. Even the drain holes in the mufflers were leaving black streaks on the undersides as moisture seeped out.

On the upside, all that soot makes identifying poor welds easier. My stock exhaust had a small leak on the connection for the H-pipe on the passenger side. It's got a nice black line where the soot is escaping and coating the outside of the pipe.

Is everyone else seeing this problem with their V6's? Anyone asked their dealer to check into it yet?

my tips get coated really quickly too. Never really thought much about it though, although i don't remember the stock ones getting quite so coated as fast.

GM has the V-6 and V-8's running super rich. I guess it is to save the cats but isn't polluting more running to rich?

The tips on mine get soot on them when I use 89 or 90 octaine gas, this dosen't happen nearly as much with 87 fuel, dealer checked computer and indicated normal..

mine does it to but i have the v8 but im pretty sure all cars r doin it and is pretty normal

I've only run Chevron 87 octane in mine. Wonder if it might have anything to do with why my car dyno's at 240rwhp rather than the 250-260hp range.

My '97 C1500 (sold) and my wife's '04 Expedition are both V8s and they had a little bit of soot but nowhere near as much as my V6 Camaro does.

Yep, I have lots of soot in the tailpipes. More noticeable after the exhaust was installed. Without a good tune we probably are running rich and not noticing the max performance that these cars can put out.

I have run nothing but 93 in my SS and have the same black soot on the tips..I am assuming that it is running rich. hopefully my new Vararam will lean it out just enough to maybe make a bit of a difference. We shall see.

Yes, the V6 runs very, very rich stock. I can't remember the exact number but I think it was something like 11.5:1 afr.

Theres a dyno sheet around here somewhere (from a long time ago) that shows the exact number...
- X

soot - Yes - lots of soot

Yeap was told my car was running really rich when asking other members about my car feeling weak. It seams to be a bad thing but is it normal for our cars, are Rey tuned purposely to run rich? It annoys me like hell, none of our other cars do this, not even close o the camaros extent

Couple of things.... My dyno guy who also tunes a lot of GM cars said he has found that GM motors like to run a bit on the rich said... that when he tries to lean them out a bit they really don't see much of performance gain and they start to ping...

The other thing to remember is the LLT is running a very high compression ratio especially when you consider it is running on 87 octane! So basically you douse things with gas to prevent pinging... IIRC...

Also... wife's Acadia has the same LLT motor.. tips are always black..

Mine is the same way. I know on my car after I installed full exhaust and cai the tips looked clean. A few days later I got a tune and now they are black.

Interesting, thanks for the good info! :thumbsup: