Been having this never ending battle for the last year.

SC400 is bogging sometimes under load (50%? or more throttle) when its warm or near warmed up.

Runs better when its cold
Wastes gas like no other.
Occasionally get MAIN O2 Sensor code even after replacing both 2 times... it still comes on.

Rotors, Cap, Wires, Coils, Plugs were done recently, 2 years ago I got a new coolant temp switch.

Any ideas?
Matt

 

check ur cat gasket sounds dumb but i fried mine. and for some reason my car would die turns out i melted the gasket completely and that was problem

 

Would you know what those O2 codes are for? Too lean? Too Rich?....etc...
If not, get your hands on a wideband and see where your afr's are at under different loads and rpms. Knowing what end condition set off your O2 codes will help.

If I had to take a guess, I would say check ecu and maf.

Good Luck Matt,

David

 

Are you running any cats? Maybe clogged?

 

I have tried a few diff mafs.

The car runs rich, so I will assume that.

Cats are gutted.

 

So essentially your problem arises when the car goes into closed loop...when it starts reading information from the O2 sensors.

Check out this thread:
https://www.clublexus.com/forums/per...mely-rich.html

It's worth a shot and it definitely helped me out.

 

Interesting, I already replaced it once due to a completely failed ECU... However, white smoke, I thought it was vapor in the exhaust, really rich under idle... I hate to even do it, but I will try my friends ECU on my car and see...

If its really the ECU again... MS3 for me.