2004 GTP Lost performance

[nickolaughagus]

Hello all,
I recently had a catalytic converter melt in my car and I removed it, drilled out, and cleaned it. Then I had the holes welded back up and bolted it back into the system. I replaced my gaskets but there was an upstream leak, and now it's pretty much open exhaust, and has been for the past month. Ever since it got clogged I've noticed lost performance, but now I really have been able to tell it lost all low end torque and just seems a tad slower even in high end rpms. Of course I have seen the code come up for o2 sensor misread, so I'm surely in open loop mode, but I am growing concerned that in the past 2 months I burnt my exhaust valves. What do you guys think? Could it just be due to loss of back pressure? Or are my valves burnt? Only other issue I've noticed is that when I am just idling it misfires and Sometimes it shifts a little weird.

Lastly, when I come to a stop, a lot of times I can feel the transmission disengaging around 5mph, and whenever I'm driving at a steady speed, and then I let off the gas immediately, the rpm actually goes higher for a split second before going down. Is that weird?

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[Scottydoggs]

if you have a huge exhaust leak right off the manifolds somewhere you gonna feel a hp loss. get that fixed. its maybe the cause of the o2 code.

the tranny is fine, thats the tc unlocking.

[nickolaughagus]

Thanks, and yeah the code is being thrown because I basically have no cat now lol.

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[Scottydoggs]

in that case fix the leak. and try the fouler trick for the rear o2. it moves the o2 out of the exhaust pipe so it gets faked out some times.

[nickolaughagus]

Okay. That's cool, I haven't thought of doing that!

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[Fivefingerdeathpunch]

Burnt valve's huh, thats a new one. You'd only do that running an open head, and not from a leak at the manifold to downpipe area.

A rear o2 code can cause problems like you are seeing, it has a cat test and will engage it often with seeing no cat and will reduce fuel mileage aswell.

Clean the throttle body and MAF sensor aswell, it can affect how the transmission runs.

[nickolaughagus]

Okay guys I cleaned my maf sensor and tb the other day, ever since then my car can't idle and a steady rpm only while driving. Obviously something is wrong with the maf, I just wondered if there's something I can do to fix it without replacing it. I resprayed it to clean it today and it got a little better but the problem persists. Also, when I shift into drive and start accelerating lately immediately after starting car, the car shakes heavily and scares the **** out of me. So now I wait a full 1 or 2 seconds to start accelerating. What should I do?

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[theaceofspades]

What did you clean the maf with

[nickolaughagus]

Maf cleaner

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[theaceofspades]

Maf cleaner

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Did you unplug it completely when you cleaned it

[nickolaughagus]

No I couldn't unplug it lol I done effed up didn't i

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[theaceofspades]

[Q UOTE=nickolaughagus;1233055]No I couldn't unplug it lol I done effed up didn't i

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Possibly lol it could have still had power and fried cause I know every maf cleaner I've seen says to unplug the sensor and let it sit for a few to make sure it has no power to it

[nickolaughagus]

I guess I'll go get a junkyard replacement. As for the shuddering, online it says that my clutch piston is going out. Is there any way that I can fix it?

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[Bluemagic]

Clutch piston?

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