No more power

[03gtdude]

Started a few weeks ago. Noticed acceleration was a bit sluggish, then it continued to escalate. Have all the common problems. Poor fuel economy, sluggish acceleration, lack of torque which affects shifts, and countless multiple cylinder misfires, most of them on cylinder 1 (over 1100). Ran a scanner on it, only code was multiple misfires, can't remember the number. LTFT was still in the positive and seemed to be in range. The odd part was the advance was bouncing everywhere, and the air/fuel ratio DROPPED on acceleration. Compared this to my dad's truck, and his held rock steady, with a slight rise on hard acceleration.
Things I've done: new fuel filter, new trans filter, new plugs and wires, re-flashed the ECM. Planning on changing the plugs from iridium to platinum later today, and possibly gonna do the coil pack.

Considered the cat, fuel pump, and fuel pressure reg. Fuel pressure voltage held firm, cat temp climbed normal.
Need answers!!

[Bio248]

$5 on a clogged cat.

[03gtdude]

Planning on pulling the 02 sensor to check this.

[Lvgrandprix2003]

Mass Air FLow may be bad. Start the car and goose the gas a couple times. then pull a plug and see if they are drowned in gas. If so you are not getting the correct Fuel to air ratio from your Mass.

[Bio248]

Mass Air FLow may be bad. Start the car and goose the gas a couple times. then pull a plug and see if they are drowned in gas. If so you are not getting the correct Fuel to air ratio from your Mass.

that doesnt happen. without the MAF it will run rich, but not that rich.

[imdaman3]

$5 on a clogged cat, code p0300 i just had the same problem with my 2003 gt

[Scimmia]

$5 on a clogged cat.

I'd love to see someone actually take that bet. I'd put far more than $5 on a clogged cat.

[Bio248]

it seems like i can solve most peoples problems by saying either 'vacuum leak' or 'clogged cat'.

[03gtdude]

Pulled the 02 sensorand there was no change. The car idles fine though. It's only under power that it falters.

[imdaman3]

did you drive it with rear 02 sensor out? thats the only way ur gona tell

[Bio248]

if the cat is clogged taking out the o2 sensor isnt going to do anything..

[imdaman3]

^^ it did on mine i took the exhaust mannifold o2 out took it for a spin and i felt the power was way better sounded like shyt tho, cut the cat off and sure enough it was clogged solid

[CTKGP09]

if it is a clogged cat you should buy my stock dp

[Jakegday]

wow a stock downpipe... with u-bend and all huh? how much would you let that go for?

[03gtdude]

Had the cat checked and the tech told me that's not my problem. Checked into it more and my LTFT is holding between -10.3 and -5.5 %. Tested the injectors and pulled to check visually. Oxygen sensor readings are bouncing cause of the rich environment, but the rear one is staying in range. Heard that it's possible to check the resistance of an O2 sensor to see if they're shot, but I've also heard this can damage 'em.

[CTKGP09]

wow a stock downpipe... with u-bend and all huh? how much would you let that go for?

i mean being 11 years old and hard to find...its like a bolt on 50 hp so i would say $500!!! ha i was looking for a drill in my garage and found the dp buried so i was pullin it out out get ready to ship to zzp while posting so i figured id make a joke

[03gtdude]

should the cat sound solid? I tapped on it, and I'm not really buying into what the tech said. No way to check visually to see if the cat's good. It's a solid pipe from the downpipe to the tips. Was wondering if there's a better way to check the O2 sensor. I get funky readings, but don't wanna blame it just yet, in case it's something else causing the rich condition.

[Scimmia]

If the tech didn't hook it up to test backpressure, I wouldn't buy it either. Just unbolt the downpipe from the manifold. It's two bolts and will tell you for sure whether the problem is the exhaust or not.

[imdaman3]

If the tech didn't hook it up to test backpressure, I wouldn't buy it either. Just unbolt the downpipe from the manifold. It's two bolts and will tell you for sure whether the problem is the exhaust or not.

never do this too much work and risk of snappin studs always pull 1 o2 sensor

[03gtdude]

Pulled the front 02 sensor and ran the car. Tons of power and no feeling of sluggishenss. Put the 02 sensor back in and left it unplugged. Not as much power as before, but no more sluggishness. Guess I can put up with the SES light until I can change the cat.