Rotten egg smell from cat when hard acceleration. 01 LS430 I had all three cat's replaced changed gas station I also only used 93 premium gas.

 

If you changed all cats and still have the smell the knock sensors might be going bad. If it is the knock sensors, then soon you will get a check engine light and youll notice the car doesnt want to accelerate. Your most likely running lean right now, thats why the smell is there. Knock sensors are under the intake manifold in the V of the motor. Theres 2 of them. They usually go bad after around 120000. One other thing is the shielded wires running to the knock sensor get dried out and crack. the bad thing about that is its one piece with the harness. Theres a lot of info for knock sensor issue in the ls430 read up on some and youll get the whole shebang.


EDIT: Also your MPG should be affected. Just a clue

 

Just curious, what was the cost of replacing all 3 cats?

 

Depends on where you go. It's a silver smell really. Cats are gonna go out. Parts is 100 to 150 labor is another thing

 

100 to 150 each cat

 

I have a 2004 LS430. I bought it used with 144,000 miles. I now have 290,000 miles out of 1,000,000 and have had a rotten egg/ammonia smell for the past 50,000 miles. The smell usually only happens when I accelerate rapidly and is overwhelming when I act like a race car driver. I have read through this forum but have not found my resolve. I have had the Cat checked and was told there was nothing wrong. I have also put in better gas since I was told but am learning that Shell might not be good. I always use 93 since I got it. I do not and have not had any check engine lights since this issue. My concern is how could so much of this awful smell get inside the cab? It is so bad that it fogs up the rear windshield as if it is a cloud of moisture which means I am suffocating in it. What causes this fog to enter the cab? It seems to me like the fog enters through the vents but it shouldn't right?
I guess I will have to try BP gas and look into the knock sensors but again how does the smell enter the cab when it should be sealed off? I do not want to get rid of my beautiful LS but I am moving and am unable to take her with me. I want to fix this bad smell issue before I sell it.

 

I also have the same issue. No CEL, O2 sensors are operating correctly, tried different gas stations. If I accelerate to around 3,000 to 4,000 rpms, not wide open throttle, just to merge on the highway. I get a terrible rotten egg smell. The smell could be coming in from the air vents since I don't notice it if the windows are up and the air vents are in recirculate not fresh air mode. I also checked the primary cats and they are operating correctly and average mpg is still decent. There appears to be a third catalytic converter after the two primary cats but there is no oxygen sensors before of after it. When I checked with a infrared temp gun I found that it may be clogged and may be the source of the rotten egg smell. The temps I measured on the primary cats were;
Left Primary Before: 386 After: 425
Right Primary Before: 382 After 424

Single "Catalytic Converter" after Primary Cats, Before: 524 After: 370

Temps are in Fahrenheit and were measure after the a few moderate acceleration runs and letting the car idle for a few minutes.

Here is the single "Catalytic Converter". Can anyone confirm it is? Or just a muffler or resonator.



On RockAuto it is listed as a Catalytic Converter.

 

I appreciate the feedback. I feel I need a better diagnosis from my catalytic system. I will have to look into that and check back.

 

I plan to do the same and will take it to a Lexus independent. Hopefully we both have some conclusive information.