When I start my car after it has warmed up I get a puff of BLACK smoke not to be confused with blue smoke from bad valve seals. This only happens when the car is warm and I start the car right after I have turned it off. If I wait about 10 min the smoke does not appear. Someone told me that this might be due to my hollowed out cat courtesy of the previous owner and I was wondering if any one else has experienced this issue. The only other thing I can think of is that the car only has a cold start function where a lot of gas is injected to aid the starting of the car when cold. Any other ideas would be great help. Thanks everyone. By the way this is on an 88 firebird 305 TBI. Thanks again.

 

I have a gutted cat on my 94 and to my knowledge it doesn't do that. Maybe it is like what you said about the extra fuel.

 

The ECM (in your case PCM) will be in "open loop" when you first start the engine along with a bit rich. While I am more familiar with older 3rd Gen ECMs, this "engine management" seems to be consistent from GM's ECM to ECM.

 

Sounds like it's just a little exter fuel. I doubt your cat would be hot enough to burn that off till it's warmed back up anyway.