does anyone know the reasons to a car backfireing, im guessing theres too much fuel entering the engine, any reason why. i know i have and o2 sensor out after the cats.

 

The o2 sensor could be your problem, I would replace that and see if it helps your problem. Is your car chipped and is your diverter valve recirculating?

 

what do you mean out?

 

backfire, or misfire?

 

A backfire is fuel in the exhaust infighting. So your exhaust is to hot, & you have to much unburnt fuel. Bad ignition timing, back engine timing (cams), dumping to much fuel.

 

out as i mean, when i replaced the cats the aft o2 sensors were holding the entire exhaust system for a few days, one looked like it got pulled out. i hope i dont have a timing problem. and yes it is a backfire, were when i let off the gas(before i replaced the cat) you could hear and see flames shooting out the exhaust pipe. after i put the new cats on, its real quiet but i have a feeling its still backfiring.

 

Its probably from that O2 sensor then.