Black Soot in tailpipe of 02 Dolphin

[DriVer]

Originally Posted by JonBrazel

What happens is condensation forms in the exhaust pipes and then gets blown back by the exhaust flow and stains the tailpipes black.

Exactly!

[jimbo16720]

Black soot means it's burning rich. Same with spark plugs.

[Jeepster47]

Jon Brazel and DriVer are correct. If your not sure with there answer, talk to Keith Shomaker at Redlands Truck and RV . Oh, and by the way my 8.1 also has black residue since new.

Ed

[Joe Gilbert]

Actually my exhaust pipes (stock) exit in front of the rear tires so the length of the pipes is not very long at all. In terms of heat I'm not sure how hot these run but you sure wouldn't want to touch the exhaust tips when the engine is running. I've had many gas motor homes with much longer exhaust pipes that never showed soot. Having said this I have no issues with the way my 8.1 runs. It is by far the best engine/transmission/chassis I have ever owned.

JoeG

[Brazel's RV Performance]

Did the other motor homes have dual 3" pipes?

[wa7hra]

Originally Posted by JonBrazel

The black soot is actually not from the engine running rich. What causes this is the design of the exhaust system. Workhorses have 2 3" exhaust pipes that run the length of the coach and towards the back it does not get hot enough to burn out all the carbon like on most automobiles. What happens is condensation forms in the exhaust pipes and then gets blown back by the exhaust flow and stains the tailpipes black.

Jon, why don't I have soot like I did before my ECM was reprogrammed by your shop?

Bob

[Mike Bronzini]

It could be that the fuel burned in the combustion chamber is not 100% efficient thus the remainder is blown out on the exhaust stroke of the engine. For instance if the fuel is burning at 90% then 10% is being wasted, now if we can figure out how to burn that extra 10% for energy that would pick up some mileage.

Mike Bronzini

[JimElliott]

Originally Posted by Mike Bronzini

It could be that the fuel burned in the combustion chamber is not 100% efficient thus the remainder is blown out on the exhaust stroke of the engine. For instance if the fuel is burning at 90% then 10% is being wasted, now if we can figure out how to burn that extra 10% for energy that would pick up some mileage.

Mike Bronzini

Mike, Perhaps just bumping up the ignition a dab would duit.

Jim

[DaveFL]

When I bought my 2000, 454 I didn't notice soot until the check engine light went on, checking codes found an O2 sensor was bad, replaced and heavy soot stopped, but it is still black, so it might be right to be black but not so much that it washes out when moisture in exhaust drips on warmup.

[Full-Timers]

You can’t compare the Workhorse W22 chassis to others. I have seen more black soot on the WH W22 chassis than others and they all do it. What I hate is when I first start it and idle while I bring in the slides and levelers and the condensation spits black soot on my cement slab.

[SpursMVP]

If it's a diesel (sounds like it's not) there better be some black soot.

[Oemtech]

Steve Brazel and I had this discussion some time ago while tuning my 8.1 for fuel trims and MAF calibration. We suspect that GM uses raw fuel to cool the CATs and thus the black sooty pipes.

[tech@brazelsrv]

I did a bit of research on this a few years ago, I tested several coaches that had the black deposits with a 5-gas analyzer and found that the exhaust was normal...not running rich. I tested under various loads, speed, rpm's on our dyno and no issues. I came to the conclusion that the design of the exhaust system along with the fuel addition to cool the cats was the most likely cause.

Steve
Brazel's RV Performance

[DriVer]

Originally Posted by tech@brazelsrv

I did a bit of research on this a few years ago, I tested several coaches that had the black deposits with a 5-gas analyzer and found that the exhaust was normal...not running rich. I tested under various loads, speed, rpm's on our dyno and no issues. I came to the conclusion that the design of the exhaust system along with the fuel addition to cool the cats was the most likely cause.

Steve, Thank you for the information. We keep bringing up this issue over the years however the answer remains the same.