Major Power Loss, Cats, Glowing....

[subparrnd]

Hello Guys,

I've got an 94 LS 400 with 114,000 miles on it. Until this last week, it's been mainly trouble free. I went out of town and came home to start the car and everything seemed fine. UNTIL i drove it. I noticed a MAJOR power loss and the engine just would not rev. After about 5 minutes of this I looked under the car and found the cats were glowing red. I've since changed the cats thinking it was the cats that were bad, the problem still exsist. My buddy who is a tech at the local Lexus dealership was baffled as well. He says that it could be the resonator that's clogged and backing everything up to the cats. What do you guys think? Any input would be greatly appreciated! TIA!

Homer

[95LS400Bob]

Unbolt the pipes at the cats and drive it. Power comes back..exhaust is restricted and go from there.

Usually it is the cats that fall apart. But I had a customer's car that wouldn't run (not a Lexus) unless we created an exhaust leak. Turned out to be a muffler baffle broke loose and basically pluged the exhaust.

Were the cats broken inside that you replaced? That material when broken loose can form a ball...perfectly round and plug the exhaust. Had that happen on an Audi. Car would idle but not rev up.

[jzz30]

you must smell raw fuel coming out of the exhaust too right? you problem most likely is the ignition coil is bad. i had the same problem with my sc400. in the morining the car started up fine, and i drove out of the driveway and got out of the car to go put mail in the mail box. and when i got back in the idle was rough and when i gave gas the tach dropped to zero and it sounded as if the car was running on half the cylinders. and they were. changed plugs, wires, cap, and rotor, that didnt fix the problem so i swapped out coils from my LS and it ran perfectly, so i found that the secondary coil was out. was 80 bucks at the dealer.

[SKperformance]

I agree with a coil possible.

If they glow red then they are getting rich. No blockage will cause them to glow unless it is tons of fuel being dumped in them.

I would let your friend do an oil change on your car if he came up with an asumption the res is bocked or any part of the exhaust for that matter.

Either a fuel injector is shot which causes a really bad idle and white smoke from raw fuel out the back . or the ignition system is not working right which usually won't cause smoke as it is not as much gas.

[jzz30]

actually when mine went out there was quite a bit of white smoke and raw fuel smell, and i only had the car on for about 5 min and the car sounded like it was hot. like i turned off the car and the heat shields were crackling( nutorious with the sc) and if you read some manuals it says that back firing can cause cats to fail. and this ignition problem is prety much a constant back fire or just a fire in the exhaust.

[hangten]

I just encountered a similar problem yesterday. I was driving home and all of a sudden I noticed a dramatic loss in power. I have a 40 mile commute, and was probably about 5 miles into it. I made it home but the engine is running rough, takes much more pressure on the accelerator to accelerate at a slower pace and the exhaust is white. It's almost as if it were reduced from an 8 cylinder engine to 4. I was just wondering if you ever resolved your problem? I have a 1992 LS400 and I didn't notice any crackling from heat and there is no backfiring. Does anyone have any idea what it could be? Would this be related to the fuel injection, ignition, catalytic converter or exhaust?

Thanks,

Mike

[maxed_out]

Red cats=unburned fuel. Not good usually.

1. Change your plugs and make sure they are all sparking properly. Use platinum dont buy crap plugs.

2.Check your air intake. Clean or replace pcv.

3. Let us know how number one turns out.

[92Lex]

What does the PCV have to do with low power/glowing cats?

[ArmyofOne]

I just encountered a similar problem yesterday.  I was driving home and all of a sudden I noticed a dramatic loss in power.  I have a 40 mile commute, and was probably about 5 miles into it.  I made it home but the engine is running rough, takes much more pressure on the accelerator to accelerate at a slower pace and the exhaust is white.  It's almost as if it were reduced from an 8 cylinder engine to 4.  I was just wondering if you ever resolved your problem?  I have a 1992 LS400 and I didn't notice any crackling from heat and there is no backfiring.  Does anyone have any idea what it could be?  Would this be related to the fuel injection, ignition, catalytic converter or exhaust?

Thanks,

Mike

←

that sounds like the ingition coil as stated above.

[srgilbert]

Looks like I have to replace at least one cat. Has anyone purchased an aftermarket cat and is so any probelms? If I get a p0430 which points to bank 1 can I get away with replacing just one cat? BTW I have replaced both front Oxygen sensors already.

Thanks

[maxed_out]

Hey sorry about that...the pcv was just a get it done type thing. My buddy says it could be related but I have to agree its probably not.

on this one, go for ignition related issue.

What about an update on whats new if anything?

Did you cook one cat?