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So I’ve been noticing that the 2007+ Lexus LS’s have lots of black soot in the tailpipe. The 460’s are the worst even the 2013’s. The LS 430’s have the least if any. The 600’s have just a little bit. Is this a bad sign for longterm reliability? And is it harming the catalytic converters and oxygen sensors? I’m curious if any of you have it on your car. Just rub your finger on the inside of your tailpipe.
Not a Lexus in the picture. Just an example. The right most finger is what the 2013 460 I tested looked like. The 600 had very little, even less than the leftmost finger. The ls430 hardly had any.
Normal for DI engines, nothing strange at all. The high compression+DI causes soot almost like a diesel engine does, that's why you are starting to see particulate filters on really new gas engines from euro-origins. You don't see it as much on the 430 since it was a port only engine that fuels richer vs a much more exact DI primary car like the 460, on DI only cars or stuff the like 460 when you go full power you can actually see a "poof" of carbon if you haven't gotten on it heavy in a while.
Last edited by Striker223; Nov 24, 2023 at 03:39 AM.
Normal for DI engines, nothing strange at all. The high compression+DI causes soot almost like a diesel engine does, that's why you are starting to particulate filters on really new gas engines from euro-origins. You don't see it as much on the 430 since it was a port only engine that fuels richer vs a much more exact DI primary car like the 460, on DI only cars or stuff the like 460 when you go full power you can actually see a "poof" of carbon if you haven't gotten on it heavy in a while.
But didn’t toyota design their DI engines with dual injection points so that it would prevent this?
But if it’s in the tailpipe, that means it’s also building up in the catalytic converters, and the ocean sensors. That’s not good.
You are totally incorrect there, it has LESS buildup than richer fueled engines in the cats and on the O2. One of the principle advantages to DI is less emissions since fueling is more accurate leading to less work for the cats and less stain on the O2s from unburnt fuel.
Again it's a non-issue, port injected cars are far more likely to kill cats than DI ones if everything is working correctly on both.
You are totally incorrect there, it has LESS buildup than richer fueled engines in the cats and on the O2. One of the principle advantages to DI is less emissions since fueling is more accurate leading to less work for the cats and less stain on the O2s from unburnt fuel.
Again it's a non-issue, port injected cars are far more likely to kill cats than DI ones if everything is working correctly on both.
just to confirm, you’re saying that the same soot that is showing in the tailpipe has somehow NOT also traveled to the catalytic converters and the oxygen sensors???? I don’t see how that’s the case because they ALL are part of the exhaust system. If what you are saying is correct then at what point AFTER the cats and the oxygen sensors does this soot form?, because I can’t think of a point where this would occur.
But didn’t toyota design their DI engines with dual injection points so that it would prevent this?
My 2008 IS250 has GDI only so Toyota did some experimentation before going with both port and direct injection. It has carbon fouling and black soot at the tailpipe.
My 2008 IS250 has GDI only so Toyota did some experimentation before going with both port and direct injection. It has carbon fouling and black soot at the tailpipe.
Have you ever had the valves cleaned? Was it labor intensive to access them?
Have you ever had the valves cleaned? Was it labor intensive to access them?
If you own an LS460 it has two injectors per cylinder (16 total) to eliminate the need for cleaning the valves by hand. One injector sprays fuel over the valves, mainly during starting and warm-up, the second one sprays into the combustion chamber. Probably this is a good reason to use just an additive and that ought to keep the valves relatively clean. A couple I use are Chevron/Techroline, plus Red line.
"De-carboning" or De-coking was as common as an oil change back in the 1920's and '30's, and that's why those old engines had their intake and exhaust valves in the engine block: to make removing the cylinder cover easily to get at the valves. But I think in this day and age owning a car that has valves that need to be cleaned is a huge step backwards. Fortunately our Lexus' engineers already eliminated the problem.
I’m still not convinced that the black soot in the tailpipe is benign. Nor am I convinced that it’s not slowly gunking up the cats or the oxygen sensors. Also when you factor in that some owners also report oil consumption issues, I still maintain the position the black soot in the tailpipe is always a bad thing.
I’m still not convinced that the black soot in the tailpipe is benign. Nor am I convinced that it’s not slowly gunking up the cats or the oxygen sensors. Also when you factor in that some owners also report oil consumption issues, I still maintain the position the black soot in the tailpipe is always a bad thing.
The oil consumption is not related at all. Read more about how DI engines run and why that soot happens, it has nothing to do with a problem like you seem to think it does. If it makes you feel any better I have several 200K+ miles LS460s that I service and none of them have issue with the cats etc from the soot issue, it's ring failure that leads to eating oil that will kill cats.
Last edited by Striker223; Nov 26, 2023 at 11:19 PM.
Noticing a bad trend. Black soot in tailpipe.
