ive got a techical question on Catalytic Converters. i purchased a 1998 jeep cherokee it had the cat cut off. it is throwing engine code for the o2 sensor behind where the cat was. im thinking this is causeing me to get worse gas mileage. should i put a stock cat back on, get a high flow cat, get dummie o2 sensors, im looking for better performance and fuel mileage? any sugestions would be greatly appreciated

 

Unless you have the ECM reprogrammed to operate with no cat or sensor, you will continue to get poor performance and bad fuel mileage. You should replace both the cat and sensor. Using a high flow cat won't be an issue and may be better. Engines work better when they breathe easier in and out.

 

Yes you will get crappy mpg and reduced HP with the cat removed. I've found from my own experience taking away any stock components from the factory exhaust will reduce mpg and HP.

Put it back on and you will be fine.

Also talk of removing a cat on this forum is frowned apon but I'll let this slide because you are considering this a mistake.

 

Well thats only because they engineered the thing to run with some backpressure...take that away and it runs lick a dead duck.....

 

So many myths. Second O2 does nothing with regard to a/f ratio or mpg. Google back pressure myths. The second O2 needs to be plugged into the factory harness to turn the CEL off and not set a code. It does not need to be screwed into anything.....just plugged into the factory harness.

 

i had also wondered if this affect gas mileage and performace