guys I know this IS a very old thread
my 94 Ls400 its pretty much sluggish wont accelerate at all on the freeway the best i do its 60 while on the gas at all times.(this issue started while driving on the freeway)
I just read the ls400 90-94 has 3 cats.
after reading your posts im leaning towards straight pipes replacements for all 3 cats .
did this fix the acceleration issue for OP and others??
ill appreciate replies thanx guys

 

Cats are not likely the problem. This thread may be of additional help:
https://www.clublexus.com/forums/ls4...read-this.html

I would also suggest inspecting the vacuum lines from the PS pump and those to the intake plenum. Leaks there will reduce engine efficiency.

Typical symptoms are poor gas mileage.

 

Yes car doesn't accelerate like normal
You must hold gas down for it to slighly accelerate, I get 12mpg at the moment
Funny when on the freeway when going down the cajon pass (downhill area on fwy coming from victorville on the 15fwy)it drives normally but climbing best it does its 45mph with pedal to the floor..hmmm

 

you have an ignition, fuel, or timing issue. fix it.

 

I agree with drifter. whats the maintenance history? Could be out of time. How old is the timing belt?

 

● could be something as simple as needing a full tuneup, i.e. plugs, wires, rotors, dist. caps
● could be engine coolant temperature sensor as RA40 mentioned above
● could be failing ECU capacitors
or several other possibilities

but one thing it's NOT going to be is your catalytic converters, one the the most reliable parts of the LS400, and replacing these with a straight pipe will not only NOT solve the acceleration issue, it will actually hurt your performance, fuel economy, and emissions, so leave those cats alone, and instead, scan the car for diagnostic codes and post them here!

 

You say that with such confidence! In my case, the cats were 100% the problem and nothing else. Replacing with straight pipes completely fixed my problem and only cost about $40, but replacing with new cats would have done the same.

Catalytic converters go bad, especially if O2 sensors have never been changed and the car has been running rich for a long time.

I believe in trying the cheapest, simplest thing first. An hour on a lift at a muffler shop for $40 is pretty damn cheap and simple.

 

My LS400 ran like it had a gokart motor in it til I removed the cats.

 

The ls400 WILL run on 4 cylinders and even idle almost normal but run extremly bad if one of the ignition coils goes out not sure wich one or if it's both but I've came across that twice its easy and not that expensive.

 

Sounds like your ignitors may have been off brand? Did you get these from your local dealership?

 

1-time poster and it's been years since he's checked in...

• Last Activity: 03-23-14 11:41 PM
• Join Date: 03-23-14

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