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2006 Lexus GS 300 - does a sooty tail pipe mean it's running rich?

I recently purchased this car and the tail pipes are black with soot, Doesn’t this mean it is running very rich? There is no smoke and it seems fine otherwise.

That is normal, the tail pipes and rear bumper are dirtier on vehicles of owners that idle their engines for excessive periods of time.

Thank you for the input, but this car never has a reason to idle long periods. We are in a small town and the only reason to sit at idle is a red light.

It will still be sooty. It hasd had 12 years to collect all that soot.

Even a new tailpipe will be sooty in short order. You are burning hydrocarbons which will produce soot.


cars with cats do that. do you have a newer car you owned that had a gray tailpipe?

A tailpipe will indeed become black and dirty because that’s the business they are in. Unless it is painting your rear bumper in black soot and has poor mileage, you probably have no problem. Clean the tailpipe tip, monitor fuel mileage and motor on. If you have poor mileage, engine codes and or that tip blackens itself quickly…then you can begin looking for problems.

Running rich would give you a Check Engine Light. Is your CEL working (lights up with all the other indicator lights when you turn to key to Run)?

I have a 2000 Ford Taurus and a 2004 Chevy Suburban. Both cars have tail pipes that are clean and dry. When you rub your finger in the pipes it comes out clean. I have owned a 1988 Ford van, a 93 Lincoln, a 2003 Camry and a 78 Camaro that all had catalytic converters and none of them had sooty tail pipes. I have lived in this area 20 years. That said, I stuck two fingers in the tail pipe on a Hundai the other day and got sooty fingers.

It just passed an emissions test. no CEL

If it passed an emissions test that included an HC test, it isn’t running overly rich. I don’t think it’s possible to judge how correct the mixture is based on the tailpipe. At least not since the introduction of electronic fuel injection and cats. My electronic fuel injected Corolla w/a cat has noticeable soot at the end of the tailpipe while my 45+ year old carbureted truck w/o a cat has very little. If you have a lot of black smoke coming out the tailpipe on the other hand, that could be in indication of a mixture problem.

The old ‘if the inside of the exhaust is white/grey, you’re good’ is back from the days of leaded gas. Lots of EFI engines leave some black soot. Direct injection engines do that even more.

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Tailpipe dip is one of my first tests when looking at a used car. Black soot is an instant pass for me. Leftover from the days prior to catalytic converters, but still works for me, weather there is any logic to it I do not know.

I was raised on checking the tail pipes for soot or smoke, color of smoke, hot or cold engine , etc. …now, with computers, fuel injection…the mechanic that checked the car before I bought it said it passed the emission test easily and insisted the soot was not a concern…I don’t know either…thanks for the input

thanks, maybe that is the answer…I guess I won’t worry about and just see how it goes…I really like the car

I think that probably sums it up …the current technology has left me behind…thanks for the input

Your engine has direct injection (one of the earlier GDI engines), with GDI engines having soot on the tailpipe is common and does not indicate a problem.

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The 3GR-FSE engine in the GS 300 was offered for only one year and possessed the same problem as the more common 4GR-FSE engine, excessive carbon build-up on the intake valves leading to misfires.

There was a warranty extension to 10 years/150,000 miles for the carbon and misfire problems that involved replacing the pistons and cleaning the valves. Five years ago replacing pistons in the 3GR and 4GR engines was a daily occurrence but the warranty on these has expired.

This engine problem has nothing to do with soiled chrome tailpipe outlets, that happens to all of them.

You just bought this 2006? So at least one prior owner? How do you know what they did with it? You’re not considering many other reasons for extended idle times. Heck, we used to sit in the car and idle for an hour or more in our driveway when we got home with napping kids. I know people that remote start and let their cars warm up for long periods before driving.

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ah… a man with the answer…Thanks FoDaddy

uho…is there anything I should to mitigate the problem?