2003 Grand Am GT has major power issues

[1SickTSI]

I have a 2003 Grand AM GT 3.4 with 166,000 miles, its hard to explain but will try. When your first taken off the car seems like its holding back, but then once you hit 3,000 rpm's with the gas pedal still pressed the same amount the car takes right off like it has a power band. Same thing regardless happens all the time under 3,000rpm. Going down the highway at 70 and you start to go up a slight incline, you give it a little gas and you can feel the car having lack of power, then you press a bit more on the gas and it kicks down a gear and goes. Then back in the same situation once back under 3,000 rpm. The car idles normal, check engine light will come on once in a while, but goes back off.

Just put a new egr valve in today and seems like its doing it worse, could be my imagination. But here is a video. I just changed the o2 sensor and EGR valve, when i ran the code on the car that is what came up with issues. Its hard to here it in the video but the car is holding back, has no power as you can see on how slow the rpms are going up, and it is bucking bad when accelerating slowly.

http://www.youtube.com/watch?v=9zf9sbPLNSg&feature=youtu.be

 

[melsg5]

Can you post the actual code ? How long since you changed the fuel filter? Have you done a fuel pressure test?

 

[1SickTSI]

codes were P0404 and P0131, i bought the car 2 years ago, i have never changed the fuel filter, no i have not checked fuel pressure.

when i unplug the egr valve, it definitely runs better at lower rpms taking off, but still same results as the video with the rpms not climbing fast, seems like the rpms will not get to 5,000 rpms when holding it to the floor as you can see in the video.

 

[melsg5]

check these links on the codes and you may be overdue for a fuel filter since you dont know when it was last done. Without sufficient fuel pressure your engine is not going to perform correctly.
http://www.obd-codes.com/p0404
http://www.obd-codes.com/p0131

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[1SickTSI]

i just removed the upstream o2 sensor and drove it for 10 minutes, hammered on it to see how it ran, it runs normal and rpm's climb right to red line fast. So that tells me one thing, Catalytic Converter is plugged. Im gonna cut the converter off and gutted or just replace it with a test pipe. Where i get my car inspected no worries there.

 

[melsg5]

OK, let us know how that goes for you

 

[1SickTSI]

yup will keep you updated, and thanx for the info as well

 

[1SickTSI]

Well i cut the Cat off today and replaced it with a straight pipe, the power the car has now is unbelievable!! i think the cat been going bad for a while, and just got worse. Cuz i cannot remember the last time my car had this much acceleration! Amazing lol

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[melsg5]

glad to hear you solved the problem

 

[1SickTSI]

thank you, only issue i have now is the exhaust is leaking on the down pipe side. The exhaust is 2 1/4 and the pipe fit perfect where the outlet side of the Cat was, but the inlet is a different size all together and i could not find no reducer that fit it snug like it should. Because it looks like its a 2 ply pipe, there is a metal mesh between the inner part of the pipe and outer pipe, im guessing to reduce the heat in the downpipe? So now i need to make a few phone calls tomorrow and see if one of my buddies have a welder i can use and i will seal it completely up that way.