Exhaust Probblem???

[1000PRIX]

K here it is

The car is shuttering/misfiring on hard acceleration, seems like only when boost kicks in... I took the front O2 sensor out today and it seemed to run a little better but was still bogging a bit. After I put the O2 back in it seemed to run alot better but still cutting out on me under hard accel. When I had the O2 sensor out the car ran the same as with it in ...

I just replaced the fuel pump and filter and plugs and Im getting spark at all plugs...

I have not replaced the wires, but the other day only under hard boosting and stuttering my exhaust manifold was glowing on the front pipe that runs to the downpipe but a week ago the whole thing glowed one night...

The funny part is this all started after I had a hole in the exhaust patched but it was after the Cat..

The funny part is when the car is in park I can rev the **** of it and the SC will kick in and it is smooth no problems...

Any Ideas Im going nuts

[blueguy]

Cat...its clogged.

[1000PRIX]

The only thing that made me doubt the cat was it still stuttered with the O2 sensor out, just not as bad...

So is ZZP the best pricing for quality around for 3" downpipe and cat???

[Thinkmoto]

The only thing that made me doubt the cat was it still stuttered with the O2 sensor out, just not as bad...

So is ZZP the best pricing for quality around for 3" downpipe and cat???

Do you expect the car to run better with the O2 out? Like previously stated the cat is plugged. Everyone told me to go with the ZZP 3" DP. I ended up gutting the cat and running spark no-foulers, no codes no cares.

[1000PRIX]

No but if the cats clogged the restricted air is suppose to escape from the hole and it shouldnt have the same stuttering symptoms if im bypassing the clat if it is clogged...Im just going by the grand prix forums HOW TO check if your cat is clogged....I didnt really understand how it was suppose to run better either trust me....So you went the cheap way....

[Thinkmoto]

Your car WON'T run better when its restricted down to an 18mm O2 sensor bung and exiting at a 90degree angle. Hell yeah i went cheap, no emissions here and the car is stock.

Either gut it or replace it with a 3" downpipe.

[1000PRIX]

Back pressure test came back better than normal apparently its not the Cat.... Any other ideas

[Thinkmoto]

What did the cat look like? Did you actually look inside? Your cat could still be on the way out. You are having the same exact symptons my ex's car had when I finally gutted the cat after speaking with Bio about it. Ran awesome after that. My car revved fine also in park and was making very good boost until it knocked. You say this all started after exhaust work was performed? Are you sure they didn't **** with the cat? Also is the patched area restricted in anyway? These cars don't like restriction in any way shape or form.

[1000PRIX]

I had the pipe from the cat to the Y replaced....I took it to mufflerman today and he hooked her up and said it read better than most cars...When the pipe was put in it was unbolted and welded to the end of the cat no idea if they effed with it

[blueguy]

So...wait...you had an entire new CATback put on it? Really?

The issue is the cat not the pipe behind it dude. Have them or a shop out in BFE take the cat out...beat all the sh1t out of it...and reweld it in. I'd go get my money back if that is what you did.

[GeosGP]

Back pressure test came back better than normal apparently its not the Cat.... Any other ideas

Where did they measure the back pressure from? If it wasn't between the exhaust manifold and cat converter, they weren't measuring in the right spot.

The cat is almost certainly clogged. That's been the general consensus from everyone here in this thread.

[1000PRIX]

UPDATE---- It was the wires and no dude I didnt replace cat back I had because I thought the cat was clogged I did that before all this...Thanks for your input guys I appreciate it

[GeosGP]

Cool, glad you got it fixed.