Hollowed Out Cat, Need help

[Pewter99Camaro]

Yesterday I changed my spark plugs and wires and hollowed out my cat. The SES light came on after driving an hour to school and then on the way home, it sometimes sounds and feels like it misfires. My brother took it to his shop and hooked it up to his computer and it said that the SES light was the cat and that everything was running fine. He checked to see if any of the wires were burnt up, but they weren't. Could this misfire feeling be because of not enough backpressure from the hollowed out cat or maybe one of the wires could be too close to another??

[ April 05, 2003: Message edited by: Pewter99Camaro ]</p>

[hockeyman]

sounds like your post-cat O2 sensor. Maybe since you bored the cat, you'll need to get an O2 sim for it...maybe.

-Marc

[davetheking]

you definately need an 02 sensor...i did the same thing wit hthe same results, then i got an 02 sim, and problems vanished! i got mine from thunder racing...it was the cheapest.

[Tyler]

performance wise... is it a good idea to gut the cat?

[JVT007]

how did u get the stock cat to come off?

[Ttop34]

Your torque is moved up in the rpm range when you take off the cat so yes, there is less at the bottom end. While racing though, you don't use that bottom end, you stay above 4,000 rpms and that's where all of the gain is so yes performance wise, it does if you have enough air coming in to support it.

[Pewter99Camaro]

My brother and I put the car on the lift at his shop and unbolted the exhaust where there is a clamp like deal right behind the seat and unbolted it from the manifolds and dropped it. Cut inlet side of cat and beat the piss out of the inside with a breaker bar and a hammer..some nasty stuff. Then just welded it back together. I am not worried about the "craftsmanship" of its appearence, just the sound because I am planning on building another 3.8 for it with a Flowmaster Cat Back or straight pipe to the Flow.