[Midnight Hour]

What causes black smoke to exit the tail-pipe at WOT? My car lets out a good size puff of black smoke and I was just making sure it was normal. I'm APU without a fuel-system and still on stock MAF.

 

[Midnight Hour]

Actually, I figured you guys would say it was because it was rich, but my car actually runs very lean. Close to 13.00..... I know that's definetly not good for it, and I don't drive it hard at all to find out if a 13.00 a/f will kill an engine, but is there anything else that could be causing the smoke or is a 13 a/f still rich enough to cause black smoke?

 

[Midnight Hour]

I've got an FJO wideband.

 

[Midnight Hour]

Yes, plugs have been changed with 3330's within 2000 miles. I've got an SAFC2.

 

[Midnight Hour]

And/or you could be blowing off carbon desposits from the motor. If that's the case, what is your oil consumption like? If it's slightly above normal, oil deposits/carbon build-up from on tops of the pistons could be blowing out, which could also look dark.

As a matter of fact, if I pull into my carport backwards, and my exhaust is facing the wall, I can spray some black shit on the wall. That could definetly be my problem. What would cause that? The short-block has about 13k miles on it.