Excessive Soot On Tailpipe

[AThomas7782]

So I've got 12k on my 09 with the 4.8. I have noticed lately there is an excessive amount of black soot on my tailpipe. It's also on my right rear quarter panel (not too excessive, but there is a dark gray haze). Has anyone else had this happen? I haven't seen a code, however, I don't remember seeing this much on other cars I've owned unless it had a lean/rich fuel mixture. Is this something to keep an eye on or am I overreacting?

 

The truck seems to run fine, except the very very slight roughness that I've heard of on many of these trucks.

[426ted]

I've noticed the same on my '09. I don't know what is normal as my last truck was on propane- cleanest tailpipe you ever did see. I sometimes wonder if it is due to a crank position sensor issue that I had, which the dealer only cleared the code. This truck is a pig on fuel in the city; 14 MPG on the last tank and driving within the speed limits and no rapid launches at the lights, personally I think mine is running too rich.

[Stex]

Not like the old days with a clean tail...I had the same worry and talked to dealer, favorite shop etc...normal for black on tail pipe end...check some other new trucks and you will see same...?? Talk to dealer if good shop...

 

14mpg all city driving is about right..city driving has a lot of idle time at lights etc...I get 17.4 on about 50/50 city/hwy and about 18.5-19.5 hwy at 70-78 mph...

[jrdifranc]

Man how ironic, I just noticed excessive soot in my exhaust as well in the past three weeks. I just put on an AFE cold air intake along with my lift and 35’s. I already had been running a corsa sport tuned exhaust and Diablo Sport Predator set on the 93 octane tune. It had been running pretty clean up until now. I even had it on a dyno when the exhaust and Predator where installed and the tuning guy said all the air/fuel mixtures were right on. It’s like it’s running too rich now, however my gas mileage is staying around 15 mpg (50/50 mix) even with the larger tires. Not sure if it’s the CAI, running at lower RPMs with the larger tires, or a combination of the two. I’m going to see if I can find a dyno wide enough in town to fit my tires to see what’s going on.

[AThomas7782]

Thanks for the replies guys. Wonder if it has anything to do with the ethanol being added to gasoline?

[FarmerDave]

Well, the 35's will bog your engine down at low cruising speeds, engine will be less efficient at pulling in air, but still needing the same amount of fuel to maintain speed. This might cause you to be rich and cover your exhaust in carbon.

[ken1mod]

Gentlemen,

 

Sooty exhaust can be the normal result of cool, damp weather. My exhaust is dead gray and dry but I live in a warm climate. Short trips can also contribute to a sooty exhaust.

 

Your fuel mileage should be checked. You might also change the front oxygen sensor if it really bothers you. As they age, they drive the mixture richer.

 

May not be a problem but keep an eye on it. Often, replacing the o2 sensor is cost effective for the above reason if over 100k miles.

 

Ken

[AThomas7782]

Gentlemen,

 

Sooty exhaust can be the normal result of cool, damp weather. My exhaust is dead gray and dry but I live in a warm climate. Short trips can also contribute to a sooty exhaust.

 

Your fuel mileage should be checked. You might also change the front oxygen sensor if it really bothers you. As they age, they drive the mixture richer.

 

May not be a problem but keep an eye on it. Often, replacing the o2 sensor is cost effective for the above reason if over 100k miles.

 

Ken

We did have a really cool winter with a lot of precip. This may be the cause of it.

[Zembonez]

Every GM truck I've ever owned had this "problem". It's mostly due to the weight of your right foot, but it's not really any sort of malfunction.