I have a one owner 97 LS400 in excellent condition. However, yesterday I noticed smoke coming from dual exhaust and odor as if mixture is not correct. I appreciate any feedback as to what the cause may be before I take it to a mechanic. Thanks.

What color is the smoke?

If the "mixtureis not correct," then it should be black smoking. If the ring seal is not correct, it should be gray smoking. Either of the two will smell odd.

A real black exhaust tip will tell about how rich the car is running. Since the car is not new, it would be wise to wipe it off and check it in a day or two. This is assuming that you can't tell by the look of it in your mirror.

As far as running fat (rich), it could be any number of things. It could be as simple as a fouled plug....fried O2 that throws the comp in safe mode and dumps fuel in the engine, a sticking injectior....the list goes on.

Has the power dropped off dramatically recently? If it is a gradual drop off, it might be a problem with oil. If it happened all at once, it is more than likely a problem with the fuel.

I just touched the tip of the iceberg with the potential stuff. There are many more problems that could be the root of this evil.

Good luck!

If you'd like a guide to see what color exhaust smoke signifies what problems, check this thread:


http://www.carforums.net/showthread.php?p=83352