Light blue smoke

ELLISMACK

MEMBER
LEXUS

Lexus 92 ls400 v8 230k miles
smokes on start up and then clears, heavy smoke after setting up for a couple of hours, had it checked
codes stated mass air flow meter, and knock sensor
had air flow meter replaced, did not help. Did not replace knock (expensive). Noticed some black
reside in tail pipe. Any suggestions?

2 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Sounds like its burning oil. Might want to bump up the oil viscosity a grade.

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Saturday, February 17th, 2007 AT 4:12 PM

KIN CHAN

MEMBER
453 POSTS

Blue smoke is oil
black smoke is running rich --> too much gas
white smoke is water or coolant in ur combustion chamber
i don't think the blue smoke have anythign to do with those 2 sensors. When is cold ur cylinder head valve seals are hard. Cuz they make out of rubber. And ur car is high mielage. Once it warms up it get soft so it seal up the oil dripping from the cylinder head to the combustion chambers. Make sense?. Good luck man.
Also. Whenever ur car misfire. Ur engine runs unevenly make some engine noise. Knock sensor detected it. Generate a code thats all it is to it. It just doing its job. Ur code is knock sensor. Not knock sensor bad. It also can imply the computer is getting some abnormal signal that its outta a good operating range --> misfire!
Hey these guys here on this website are really good guys. They let me come aboard to be part of their team. Try to give em' some support if u think my answer worth anything. Thanx man.