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Help! 91 Ls400 Lack Power, Glowing Cats!


J-Roc

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Hi all,

My friend has 91 LS400 w/the 4.0 V8 w/180k and we can't figure this one out :cries: The symptoms are no engine codes thrown, lack of low end power, and the cats are glowing to the point of burning the excess oil and the engine bay is smoking ALOT! Also, acceleration from a stop results in a "put-put-put" sound from the exhaust. I've changed caps/rotors, spark plugs, spark plug wires, new, air filter, pcv valve, cleaned out TB, cleaned out EGR valve, replaced cats. The pickup is better, but the cats are still glowing when the engine is revved. What else can I do? Check timing? :( Any pointers are greatly appreciated! Thanks all...

If I have read the post correctly he allready replaced the cats........ Why don'f folks read the complet post????

Sorry I have no thoughts on what to check. ?The red cats tell me there is unburned gas or oil getting into them, but I have no idea of why?

It was a thought :blink:

i had same problem with 92 ls400. Don`t know if this your problem but mine was a bad ignition coil. just one. you have two one on each bank. my cats would glow red real bad. no power could not go over 25 mph.
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Hi all,

My friend has 91 LS400 w/the 4.0 V8 w/180k and we can't figure this one out :cries: The symptoms are no engine codes thrown, lack of low end power, and the cats are glowing to the point of burning the excess oil and the engine bay is smoking ALOT! Also, acceleration from a stop results in a "put-put-put" sound from the exhaust. I've changed caps/rotors, spark plugs, spark plug wires, new, air filter, pcv valve, cleaned out TB, cleaned out EGR valve, replaced cats. The pickup is better, but the cats are still glowing when the engine is revved. What else can I do? Check timing? :( Any pointers are greatly appreciated! Thanks all...

If I have read the post correctly he allready replaced the cats........ Why don'f folks read the complet post????

Sorry I have no thoughts on what to check. ?The red cats tell me there is unburned gas or oil getting into them, but I have no idea of why?

It was a thought :blink:

i had same problem with 92 ls400. Don`t know if this your problem but mine was a bad ignition coil. just one. you have two one on each bank. my cats would glow red real bad. no power could not go over 25 mph.
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  • 5 years later...

This article on us.lexusownersclub.com is bookmark worthy in my opinion. It's worth saving for future reference. It's fascinating reading with many valid points for contemplation. I have to concur on almost every point made within this article.

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