PDA

View Full Version : Black Smoke on tailpipe?


Evrgrnmtnman
03-12-2008, 12:09 PM
I understand that black smoke on the tailpipe is a sign of the motor running rich on gas??? Is this just caused from living on a Glacier and the air is cold??? I guess the TPS and Airflow Meter adjust the richness due to cold air?? I am asking if this is a correct assumption........
Thank
88,22RE........

DaveInDenver
03-12-2008, 12:17 PM
Are you talking clouds of black smoke here? Any time my truck has been rich I could smell the gas more than see it as smoke.

Evrgrnmtnman
03-12-2008, 12:21 PM
Are you talking clouds of black smoke here? Any time my truck has been rich I could smell the gas more than see it as smoke.
It's not blowing clouds of black smoke out the tail pipe. Just notice the color on the pipe is black. Don't seem to smell gas....

DaveInDenver
03-12-2008, 12:30 PM
Oh, I wouldn't be too concerned. Your engine does run rich sometimes, especially in the morning cold. For the first few minutes the mixture is very rich because the gas isn't vaporizing very well yet inside a stone cold engine. The cold start injector on our engines adds even more fuel and the ECU is pumping gas into the combustion chambers. It's the brute force approach to getting the engine to start and run when its cold. So the exhaust pipe gets coated with that stuff. If it's running rich after you get it warmed up, then you have to start troubleshooting (standard stuff, check the TPS adjustment, verify the EFI temp sensor, AFM, O2, EGR are all working, adjust the valves, ignition, plugs, cap, rotor, plug wires). I'm talking like after driving a few minutes on I-70 sort of warmed up, not just that the temp gage has just started moving. If you think the exhaust is bad, you probably shouldn't look through the throttle body into the intake plenum. The nastiest black goo mix of unburnt fuel, EGR gases and PCV oil. Yuck.

Evrgrnmtnman
03-12-2008, 01:37 PM
Oh, I wouldn't be too concerned. Your engine does run rich sometimes, especially in the morning cold. For the first few minutes the mixture is very rich because the gas isn't vaporizing very well yet inside a stone cold engine. The cold start injector on our engines adds even more fuel and the ECU is pumping gas into the combustion chambers. It's the brute force approach to getting the engine to start and run when its cold. So the exhaust pipe gets coated with that stuff. If it's running rich after you get it warmed up, then you have to start troubleshooting (standard stuff, check the TPS adjustment, verify the EFI temp sensor, AFM, O2, EGR are all working, adjust the valves, ignition, plugs, cap, rotor, plug wires). I'm talking like after driving a few minutes on I-70 sort of warmed up, not just that the temp gage has just started moving. If you think the exhaust is bad, you probably shouldn't look through the throttle body into the intake plenum. The nastiest black goo mix of unburnt fuel, EGR gases and PCV oil. Yuck.

Makes perfect sense!
Thanks