!995 SC400 that my 16 year old daughter drives. The car was running great until she put mid grade gas in it. After that it sounded like it was missing on all cyls and no power. I put octane booster in it and its alot smoother but now the cats get red hot.I have 2 new cats coming but what else should i do, 02 sensors etc.

 

your daughter has nice choice in cars, if it was mine id put octane booster in it ( as you did ) and just let it idle out. best of luck!

 

Sounds like she got some bad gas as I don't think just putting mid grade would cause this. Sounds like some other variables are causing the missing symptoms other than just a lower grade octane.

 

She's running rich enough to get the cats hot, there are other issues abound. See if there are any codes in the ECU.

 

no CEL but I will check further

thanks

 

The problem is not the midgrade fuel but rather another problem such as bad gas as mentioned above and I have run my sc400 on 87 fuel for thousands of miles with no problems to speak of.

 

I put 10 gal of the gas in my chevy pickup and refilled the sc with 10 gal of fresh 92, the car idle is smooth but driving it, it has zero power and the cats get red hot. The truck is running great on the 10 gal of gas out of the car.

 

https://www.clublexus.com/forums/per...r-hot-cat.html
https://www.clublexus.com/forums/per...red-hot-2.html
https://www.clublexus.com/forums/per...-engine-2.html

 

Thanks for the help everyone, I found a pinched coil wire under the cover grounding to the block. Changed it and is running great. I'm still going to change the cats when they come in however, getting them red hot is never a good thing for them.