Catalytic Converter - Regular vs. Premium

[gathermewool]

Originally Posted By: rslifkin
Now that I think about it... I should have my dad try a tank of 93 in his 05 Camry V6. His tailpipe is definitely sooty, and it stinks like heck if I'm driving behind him and he goes WOT. It doesn't ping though, and runs like a champ with about 125k miles on it (he drives a lot).


If it's not pinging and doesn't require premium, then it won't do a thing. If you look around, there are many, many cars with sooty tail pipes - it's normal. If you smell something funky, then maybe he should check other things that could be leading to incomplete combustion, such as plugs.

Does it smell like rotten eggs? Coincidentally, I was behind an '01-'06 Camry and it smelled very sulfuric. He probably has a CEL and needs to replace his cats.

 

[beast3300]

You are not going to hear ping or knock on modern cars unless it has 82 octane in it. Instead you have "silent" knock which is when the knock sensors hear knock and pull timing. Yes this saves the engine, but for timing to be pulled, knock has to be heard first.

I don't know how the PCM fuels those Toyota or Lexus engines. For example: On my Buick the [wot]fueling is set. It doesn't add or subtract WOT fueling that isn't programmed in. It will on the other hand compensate for weather, load, etc under normal driving via fuel trims.

All the w-bodies that I have hooked up my programmer to knock on stock tune. And don't count on stock PCM/ECU/ECM (whatever your manufacture calls it) to fuel correctly under all situations.

 

[rslifkin]

gathermewool - Those newer Camrys all do that under heavy throttle. It's definitely the sulfuric rotten egg overloaded cat smell. No CEL, and the car has done that since he bought it new in 05 (no worse now than it was then). Pretty much any new-ish Toyota / Lexus I've been behind on a highway on-ramp produces the same stench.