Black Smoke Upon Shifting
12-27-2005, 02:42 PM
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Black Smoke Upon Shifting My car is blowing black smoke every time it upshifts under hard acceleration. There's a lot of carbon in the tailpipes, but nothing else. It sounds like I have an exhaust leak also, but I doubt that would acount for the smoke out of the tailpipes. It doesn't blow a lot, just a noticeable puff every time it shifts up. No SES lights and it doesn't feel like theperformance has been affected. Anybody have any idea why it's puffing smoke? Could an exhaust leak cause it? Thanks for your help.
12-27-2005, 06:30 PM
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Rich condition = black smoke. What's your A/F numbers look like (if you know)?
An exhaust leak near or before an O2 sensor could cause an extra rich A/F. Introduction of fresh, unmetered air (pre-O2 sensor) in the exhaust system during closed loop will make the PCM think it's running leaner than it actually is, hence adding more fuel than necessary and causing a rich condition.
An exhaust leak near or before an O2 sensor could cause an extra rich A/F. Introduction of fresh, unmetered air (pre-O2 sensor) in the exhaust system during closed loop will make the PCM think it's running leaner than it actually is, hence adding more fuel than necessary and causing a rich condition.
