2005 Tahoe—Black smoke under acceleration

[dsf260]

I have a 2005 LT 5.3 that under heavy acceleration (i.e. accelerator to the floor) puts out a nice cloud of black smoke from the tailpipe.

The truck is not showing a 'Check Engine' light and seems to be running fine other than this problem. The car has 85,000 miles and hasn't had any issues with the powertrain (knock on wood). I have owned the car since new, and have taken good care of it (regular oil changes w/ synthetic, K&N filter, regular recommended maintenance, light service, etc.)

I haven't replaced the plugs yet, but was going to do that and the other 100,000 service items within the next 5-10k miles.

I know black smoke is a sign of a rich mixture, and the fact that it only happens under heavy load supports that idea.

Given my current economic situation, I would definitely take on some of the work myself. I am new to working on my vehicles, but certainly want to learn. I do know my way around an engine bay to some extent, but I don't have any real experience in doing anything more than basic maintenance.

Any advice on where to start would be appreciated. Thank you.

 

[M3PO]

Can you see this black smoke in the daylight?
If I romp on it at night with a car (headlights) behind me, I can see a little in the review mirror.
If you can see black smoke in the daylight, I would think you are rich. On the other hand I couldn't see how you would have a CEL.
Has your fuel mileage changed?

 

[TheYuk]

mine used to do this then I did plugs, wires, fuel filter, and oxygen sensors and it went away.

 

[04SS99Denali]

my yukon does it on occasion. im thinking its the 02's going. 02's control fueling

 

[dsf260]

Thanks for responding.

This hasn't happened again, so I think it just was some built up soot that was blown out under hard acceleration. I am usually tooling my kids around or driving to work, so I generally don't hammer the accelerator too hard. 2500 rpm is my normal max. When I saw the "smoke", I was at about 4500 and rising.

I guess I'll make sure I hit it every 2000 miles or so to clear out the exhaust. J haven't seen any sort of drop off in gas mileage, other than a basic drop when I changed tire brands.

I do need to do the plugs soon, as well as the rest of the 100k mile service. I'll swap out the 02 sensor in the exhaust just to be safe as well.

Thanks again.