ok here is what I don’t understand. If it is direct injection then that process happens in the combustion chamber BEFORE the cats and the o2 sensors. So that means that any by product that results from DI has to pass from the exhaust of the engine , through the exhaust system and out of the tailpipe.
Also I realize that not all soot is equal. There can be soot from oil consumption. Soot from running too rich. And soot from carbon buildup. So the soot in a tailpipe is from one of these reasons. And none of those reasons are begnin. If there is any other reason for soot that I’m not aware of please tell me. I did read the post from swfla that said that soot forms and collects as it cools down. Well if that’s the case, then what kind of soot is that? And why don’t all cars have it DI or no DI? Because the ls430 I once had had no soot it wasn’t DI but it did have exhaust gasses that cooled after the cat as swfla notes. This is what I’m not understanding.

 

You owned an ICE car that DID NOT have soot in the exhaust pipe? Lies.

 

yes. I already mentioned one example in my op.

 

Check again then, the inside of the 430s pipes get just as black and sooty. I owned both at the same time and have seen over a dozen 460s and 6 430s

 

not from my experience and I’ve checked several. Also your claim would contradict those on here who claim that the soot is because the engine is DI of which the ls430 is not.

 

Read what people have posted again.

The DI engines run more precisely and with far higher compression than a port engine ever can, that leads to more pute exhaust gassses that generate more soot once it cools/nears end of pipes since there is less unburnt fuel fo act as a cleaner.

The 430 when floored floods far more fuel, if you never get in it that hard though it will look exactly the same and if you have a lot of miles it will also be the same. My 430 had 260k on it when I got rid of it and it was just as black and built up as any other car. Something like my truck is fueled so aggressively that cold starts have it literally spitting gas out both pipes....and it stays perfectly clean as a result.

There isn't an issue with the way the 460s work, it's normal. If it concerns you when you don't understand the way it's designed then replace the engine or car for your peace of mind. More precise fueling, higher CR, and better emission tuning all result in more soot since a "perfect" running engine should only produce carbon and water. The closer you ge to that the less extra unburnt fuel (a cleaning agent) you have running past the cats and to the end of the pipes

This is the last time I'm going to try and explain this since you clearly haven't looked into how engines work yourself.

 

Ok. The more detail in this explanation actually helped me. That said let me ask you this, since some ls460’s do burn oil (most do not) is there a way to tell the soot apart? Does oil soot have a different smell or texture than the harmless soot you described? One thing I’ve noticed with oil burners is that it leaves black marks on the bumper itself along with the soot so that’s one distinction. I know that soot from running too rich leaves a fuel smell. So I guess the real question is how to identify “harmless” soot from the “non-harmless” soot.

 

And as others on here have assured, it’s nice to see that reliability has indeed not suffered. Consumer reports has a perfect score for the LS in almost every category