black smoke exhaust
Thread Starter
Intermediate
Joined: Apr 2009
Posts: 36
Likes: 2
From: las vegas
black smoke exhaust
Hi all, just changed the o2 sensor on my 85 vette. now when i start it up it has black smoke from the exhaust. Light at first then it gets worse as it warms up, then it gets really bad, specially if you rev it, then it goes back to light when it reaches normal temp. i changed it cuz i failed smog test. Its new and didnt smoke before i changed it. Do you have to disconect the battery after changing the o2 or is my new o2 just defective? Please help
Le Mans Master
Joined: Feb 2005
Posts: 6,485
Likes: 566
From: Clearwater Florida
..... As the OP describes it ... the exhaust smoke gets lighter after it warms up ... just about the time it goes into closed loop and the O2 sensor goes to work ??? ........ There's something else going on to over-enrich the system ... bad injectors or fuel pressure regulator ... or a completely blocked air filter / intake ..........
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
..... As the OP describes it ... the exhaust smoke gets lighter after it warms up ... just about the time it goes into closed loop and the O2 sensor goes to work ??? ........ There's something else going on to over-enrich the system ... bad injectors or fuel pressure regulator ... or a completely blocked air filter / intake ..........
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
..... As the OP describes it ... the exhaust smoke gets lighter after it warms up ... just about the time it goes into closed loop and the O2 sensor goes to work ??? ........ There's something else going on to over-enrich the system ... bad injectors or fuel pressure regulator ... or a completely blocked air filter / intake ..........
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Racer
Joined: Aug 2007
Posts: 267
Likes: 0
From: Springdale Arkansas
Black smoke =fuel. White smoke =oil Also some of these sensors have built in heater circuits To aid in getting the sensor hot enough To quickly reach closed loop control (where the ecm takes control and adjust the fuel to air ratio automatically)
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Joined: Mar 2008
Posts: 2,351
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From: Delta B.C. Canada
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..... As the OP describes it ... the exhaust smoke gets lighter after it warms up ... just about the time it goes into closed loop and the O2 sensor goes to work ??? ........ There's something else going on to over-enrich the system ... bad injectors or fuel pressure regulator ... or a completely blocked air filter / intake ..........