A friend of mine picked up a 2002 LS430 not long ago, and one of his catalytic converters has gone bad. Forgive me if this is a dumb question, but on the LS430, a car of which needs back pressure, will removing both cats and replacing them with standard piping reduce performance? Its illegal, I know, but we are in a state that does not inspect, and with almost 5 mufflers under the LS430, it wouldn't be loud enough to assume anyway.

Also... after filling up with Shell V-Power (93) several times, I've noticed that my car will start to smell like sulfur if I've been accelerating quickly (Not even at WOT). From what I understand, this is a Catalytic Converter doing its job, and for as long as I used Chevron Gasoline, I never once had this disgusting problem. Can anyone recommend a gasoline brand with low sulfur? This problem has been occurring a lot lately, and I'm hoping the sulfur-related smell is because of the fuel I filled up with.

Thanks in advance.

 

I suspect that lowering back pressure will shift the torque curve to the right, netting lower low end torque. I don't know why this is, but I've seen it happen on a couple vehicles I've had high flow exhausts installed in. I'm very leery about messing with the exhaust anymore. Plus I no longer feel the need to have a vehicle that rumbles - well at least not my current vehicles.

I use only V-Power and have never noticed a sulfur smell. I wonder if you're starting to have a cat problem.

 

You also might have a problem with the engine management.
As I understand it, there is an O2-sensor before the cat and one after it.
When you remove the cat, the O2-sensor after the cat will not sense what it used to sniff (or what it is supposed to sniff), so that could disturb things.

Jac

 

My engine light just came back on again(just before emissions time). First it was my plugs then fuel injector #5 now its code p0420 I'm gonna try the sensors up front and a induction cleaning if that doesn't work ill be gettin a cat. And I also have that sulfer smell when steppin on the gas aggressive at times.

 

rear (after cats) o2 sensors only control the condition of cats themselves, and have nothing to do with engine management... BUT if p0420/0430 conditions detected and DTC's are set (bad cat/no cat) ECM will default to more 'safe' fuel maps thus increasing fuel consumption and reducing power...
i removed my cats long ago and used 'tubes' to fool the rear o2's - got the 'tubes' (or whatever they called) off ebay for like 10 bucks.

 

I am new to the forum and am always trying to get information pertaining to the ls430. Thanks in advance for any feed back. I am in FL. and want to remove the CAT but fear lost of engine power or excess gas consumption. Is there any truth that these things occur when one removes the CAT? Then, the "tubes" that are used to fool the o2's who is the seller, or what do I search for on ebay?

 

If you remove the cats your gas milage will go way down I did it on a 1981 olds.

 

if you remove the cats, gas mileage goes down, performance goes down, and it is one of the dumbest things a person can do to their Lexus!

also, LS430 cats almost never go bad, so I strongly suggest he get a second opinion on whether that is even the problem - a good mechanic can measure back pressure before and after the cats

 

cats removed 3 years ago (gone bad, yup). o2 spacers installed. no changes to mileage and power whatsoever. case closed.

 

case back open

If you had no changes to power or mileage after removing the cats, then your car wasn't running right in the first place, and you were getting neither factory new power nor mileage! - Your ECU and the other parts of your engine were tuned and engineered for a specific back pressure, you change that, and the numbers suffer accordingly, it's just basic science. - There is an old saying, "You are entitled to your own opinion, but you aren't entitled to your own facts!"

 

you do not understand the mechanics of proper cat removal, and i won't explain it here in depth, cos most ppl here are just users.
flame away.

 

Thanks for your feedback it is greatly appreciated and I found a site selling the o2 spacers though I am not sure which size to order. Tell me, my 01 430 give me about 360 miles from a full tank of premium gas. I am aware that some owners get at least 400 from there full tank and they drive their car more than I drive mine. I do not have much stop and go drives nor highway, on the highway I average 65mph,with 113k miles right now. Hope when I deal with the cat. I get better mileage. What do you average per full tank with your ls?