bori1006

I recently purchased a 1994 Lexus LS400. Reason being miles were low , price was great and only one owner. Now the problem i am having is the car smells like gas when it is on and seems to be stalling when driving. Took it to the mechanic. It has no check engine light on. No codes come up when it was checked. Recently got a tuneup which the check engine light was on prior to tuneup and went off after tuneup was done. Def driving better then it was before tuneup but still not 100%. Also recently changed front catalytic converters both of them. But i notice the converters are lighting up i guess over heating because they are turning bright red to orange color. Any ideas what the issue could be. I would appreciate any helpful info.

2GenLS4

That's a new one to me! Quick question, is your headers getting that hot? Did you replace the cats with OEM, or cheap knock-offs.
Our LS400's are very sensitive to the exhaust system.

Stalling is unlikely to be related to exhaust, however a clogged catalytic converter could be a possibility to why your engine is cutting out at idle/low rpm, I'd shake your cats and see if you can hear anything shaking around in them.

When I had my UCF10, I had a stalling issue as-well however that was fuel related, and would most of the time start right after.

dicer

Running rich and could be ecu caps or cold start valve leak, O2 sensor, ECT. Not saying it is for sure any of them, just ideas. Also fuel pressure check is in order.

bori1006

I purchased walker brand catalytic converters. Was told they are the best brand around. But they were just installed. Are OEM parts best? I would love to have this car running at 100%. I feel it would be a beauty if she ran smooth and had all the proper necessities. I rather purchase the proper pieces for it. I am new to this forum and trying to learn about this car. Thank you for your help. I greatly appreciate it.

bori1006

I def will have the fuel pressure checked. Read a thread about that yesterday. Will be taking her back to the mechanic Monday morning. He said he is going to fully check the engine which will take a few hours for him to check everything. Hoping i will not hear it needs a new engine.

djamps

The reason the cats glow is due to excessive unburnt fuel. I'd start by figuring out which cylinder(s) are not firing correctly and go from there. A relatively simple test is to unplug then re-plug coil packs (or plug wires) one at a time, if you unplug one and there is no change in idle, that is your culprit. If you're getting BOTH cats glowing, then it's probably not a coil, rather a system-wide fueling issue. Check coolant temp sensors, o2 sensors, fuel pressure, ect...

bori1006

Thank you will def make sure they check for everything that has been suggested from everyone. Gotta star somewhere. Will post tomorrow the findings that have caused the issue.