Cat. converter

I'm pretty sure my cat. is somewhat clogged after reading the threads on here, so my question is do I have to replace it? or can I just cut it off and just use a piece of straight pipe? will there be any adverse effects if I do this? thanks guys.

....can I just cut it off and just use a piece of straight pipe? will there be any adverse effects if I do this?


A hefty Ticket. Its not worth it. Just go over to ZZP and buy a high flow weld in cat and have your nearest exhaust shop weld it in for you. Or else you can buy a downpipe.

I herd if you dont get the correct type of cat for the engine the car can catch fire from the cat overheating or something

I herd if you dont get the correct type of cat for the engine the car can catch fire from the cat overheating or something

I'm not sure your car can catch fire from the wrong cat. Maybe a CEL on. The cat can get red hot, melt, or cause a fire due to an overly rich condition. Which is why it is important to fix missfire conditions assap. Especially ignition related ones.


To the OP. What year is your car and how many miles are on it? Your cat might still be under warrenty.

It is never a good idea to remove the cat from a car for the reasons already stated. Because cats must meet the same general specifications as OEM you shouldn't have any issues with installing an aftermarket one on your car. My GTP has a 3 inch magnaflow cat on it and it runs perfectly. No overheating or anything else. I have both O2 sensors in place and have not had a CEL since it was installed.

if you take it off then i think you need the O2 Emulator (http://www.zzperformance.com/grand_prix/products1.php?id=834&catid=110) ..

but with the cat do you get a p0420 code?

with the emmisons are controlled by the goverent.. my cat stop working at 65k and i took it to the gm dealer. i had to argue with them. bec i had 2 half inch catback. other wise i got a new cat for $27 ..

i think the fed warranty is 8-year 80k. i think..

Ok after changing the plugs out last night to see if this would help any? and also cleaning the MAF, the car ran pretty good (not perfect) for about 5 minutes, then back to crappy as its been. it wont even hardly get above 50mph all the while hesitating like it want's to go but doesnt. so my question now is if you had to bet, do you think its a bad MAF or a clogged cat? as it seemed to run good untill it heated up? (again its a 97 gtp w/ 155k) and in addition unplugging the MAF does not seem to make that big a difference(maybe just a little)

if you had to bet
My bet would be your fuel pump. Did you check the fuel pressure at the fuel rail?

For some reason, my Edit button does not allow me to change my post. Anyway, if you can go 50 MPH, but not 60, and your CAT is plugged, I would think you would hear some kind of hissing coming out prior to the CAT that would make it sound like you're driving an air-pressure powered car.

no I havent but I had the fuel pump replaced about a year ago, also the more gas I give it the more it bogs down if that helps? and I do notice that the sound of the exhuast is not sounding like it's clear, kinda of like sputtering if you will. also if its in park or neurtal I can rev it up a way then it starts to studder, and the exhaust sound is more clear like it should be?

Try unplugging the MAF and driving it that way. If it drives better with the MAF unplugged, then it is bad. If nothing changes, then the cat is most likely bad.

Just want to give an update, so I had my cat. changed today and that was the problem..! it runs 100 times better now, so I just want to thank every one on here for all the tips and pointers, and can't say enough how awesome this site is..! so thank you guys =)

Nice work, I'm not sure if it was mentioned, but GM was offering an extended warrenty of 120,000 miles on I think 2002-2005 GP's for Cat converter problems. I hope you didnt pay out of pocket if you didnt have to.

Yea I did see that, but mine is a 97 with a 155k so either way..