LS - 3rd Gen (2001-2006) Discussion topics related to the flagship Lexus LS430

Driveabilty problem! Help

Old 02-27-16, 01:26 PM
  #61  
Slvr surfr
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Originally Posted by Coulter
I tend to think what happened is your exhaust got clogged from the snow, the heat couldn't escape so it melted your cats and that created the restriction.

I don't think it had anything to do with the replacement cats being defective, OEM ones would have likely done the same thing if that had been clogged up.
Very true! I just thought by being new it would've gave up a better fight lol. Not sure if Rock will cover this particular situation but it wont hurt to ask. That said, last night after installation of the new front cats i do notice the exhaust flow is a lot better. The engine seems stronger also. Maybe the fronts were also on there're way out and were restricting flow along with the rear one. Before, i could hardly feel or see any vapor from the rear. Now, i can see vapor although the output still feels pretty weak.

What i may do is just grab a universal converter, have the shop cut out the bad cat and weld in the new one and be done with it. It's cheaper than buying a whole new y-pipe.

Question tho! Can that secondary cat be deleting without major consequences? Will the car be louder without it even tho the resonators and mufflers are still intact? Is there a specific type that it has to be replaced with?
Old 02-27-16, 02:00 PM
  #62  
Coulter
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Originally Posted by Slvr surfr
Very true! I just thought by being new it would've gave up a better fight lol. Not sure if Rock will cover this particular situation but it wont hurt to ask. That said, last night after installation of the new front cats i do notice the exhaust flow is a lot better. The engine seems stronger also. Maybe the fronts were also on there're way out and were restricting flow along with the rear one. Before, i could hardly feel or see any vapor from the rear. Now, i can see vapor although the output still feels pretty weak.

What i may do is just grab a universal converter, have the shop cut out the bad cat and weld in the new one and be done with it. It's cheaper than buying a whole new y-pipe.

Question tho! Can that secondary cat be deleting without major consequences? Will the car be louder without it even tho the resonators and mufflers are still intact? Is there a specific type that it has to be replaced with?

I would think you can delete it without issue, I had a car previously where I deleted one of the cats but kept the other. I believe the downstream sensors are before the Y-Pipe, so it shouldn't have any problems.

It might be a bit throatier with the noise, but I doubt you'll notice. Might even like it. With the main cats still on there along with the factory mufflers and resonator, it's still going to be a quiet exhaust.
Old 02-27-16, 02:48 PM
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Originally Posted by Coulter
I would think you can delete it without issue, I had a car previously where I deleted one of the cats but kept the other. I believe the downstream sensors are before the Y-Pipe, so it shouldn't have any problems.

It might be a bit throatier with the noise, but I doubt you'll notice. Might even like it. With the main cats still on there along with the factory mufflers and resonator, it's still going to be a quiet exhaust.
How about from an emissions standpoint? Do those secondary cats help with pollution? If decide on just replacing it with another, will any universal converter do?
Old 02-27-16, 05:39 PM
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Originally Posted by Slvr surfr
How about from an emissions standpoint? Do those secondary cats help with pollution? If decide on just replacing it with another, will any universal converter do?
They help, but most states emissions test with just the OBD connection after 1996, so unless you have a check engine light that's on, you pass emissions. Since the downstream sensors are before the Y-Pipe, no codes should be thrown.

Some states actually put a sniffer on the exhaust (usually on pre-1996 cars) but even then, I would bet many cars would pass without the secondary catalytic converters.
Old 03-17-16, 06:11 AM
  #65  
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Thumbs up Finally!!!

Finally got my situation situated. $250 later the bad middle cat was replaced with an universal unit (pics below). Had it cut out and welded in. Took about an hour at the same exhaust shop that did my other exhaust work. I took the liberty of painting the pipes black but ran out of paint so i'll finish later. It just looks better blacked out to me. My power has returned with a vengeance. The substrate inside the faulty part had broken loose and created blockage with rattling. Although im happy it's done, i wished i couldve found this out first. By throwing parts at it I replaced both front cats, a coolant sensor, a B2S1 oxygen sensor, and a MAF sensor but given my mileage and age these parts were about due to be swapped out anyways so no big deal. With all those new parts on it i can really tell the difference and mpg's instantly went up. Glad this is now over so i can get back to putting the engine mounts and revitalizing my suspension in which the ball joints, tie-rods, rack bushings are still due. Also a new set of oem 18's will land before the summer hits.
Attached Thumbnails Driveabilty problem! Help-wp_20160316_001-1-.jpg   Driveabilty problem! Help-wp_20160316_002-1-.jpg   Driveabilty problem! Help-wp_20160316_003-1-.jpg  
Old 03-17-16, 06:35 AM
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Great job, Slvr ... thanks for coming back to share your experience too.
Old 03-17-16, 01:16 PM
  #67  
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No problem. If it wasn't for you guys, I would've spent a whole lot more.
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