Crappy acceleration 3.8V6

[bluebowtie67]

well, i've got a 2001 Grand Prix GT with the 3800 V6. It starts great and idles good. If you rev it up a little it's fine... but if you really press on the gas it revs to about 3900 rpm and then starts to sputter and will not go above 4000 rpm. It's a fast sputter/popping... and when i let off the gas it kind of tries to die unless you flutter the gas. When i'm driving, it's okay under light acceleration. But if I try to take off fast or go up a hill or something, it bogs down really bad and if i gas it, it downshifts until it reaches about 4000 rpm and then it does what i described above. I have NO check engine light of any kind. At all. I've replaced the tranny filter and fluid, fuel filter and spark plug wires. The air filter is good. Everything seems to be okay,.. nothing crazy.. however, i'm not very familiar with these cars, but the exhaust is very sulfury and very very hot. I think the catalytic converter is the culprit. or at least part of it. Maybe the O2 sensor went bad and then made it run wrong and clogged the cat. No clue, but that's what i'm thinking. If anyone has had this problem or has any input, it would be appreciated. thanks in advance.
tOny

[A-ROC]

It`s sounds like you have a problem with a worn out rusted resonator! Try adding fuel injector cleaner and change air filter!

[A-ROC]

you can~t clog a cat. I`ts clogged from the factory with a dense foam material. wow it kinda sound like you`ve been putting bad gas in your car. because you`ve covered your bases. i`m in canada. and the Pioneer gas is good but if i put Petro-Canada in it runs like shit.

[Rufo]

That's not true, you can clog a cat. Several GT owners I know have had it happen to them. I'd definetly get that investigated, chances are you can get it replaced under warranty.

[caruch6392]

i have a 2000 GT. i believe all cars from 97-03 (at least from what i know) have a neutral..and park..rev limiter. if you are in park or neutral and floor the accelerator it does actually stop it at 4000rpm and does sputter b/c it kicks in the goverener. it's not good to spin a free revving engine that high anyway. although you said it does this while driving...which should NOT happen. i can' pinpoint the problem but i definately know there is a rev limiter in neutral and park.

[mrmt523]

the rev limiter runs back into the 95s too, now that i think about it into the 93s even, caruch is completely right, its to stop you from over revving the engine, if you over rev it it will cease/scuff and that is a very expensive way to show someone it still sounds good at high rpm or whatever but anyways, maybe the gear selector sensor for this rev limiter is messed up...something like that...

[AKWE-gt]

after driving for awhile check the catalytic to see if its glowing red, if it is then it could be plugged up. but it sounds like your problem could be more timing related. like when the timing chain stretches and it retards the timing. i had engine rebuilt and the guy put the cam in wrong so the engine wouldn't rev higher than 4800rpm, it would get there and just sputter like yours.

[MCSSPORT]

I seem to be having the same problem with my '93 GP. Mine seemed to be more of a progression though. Before the car got to this point, when I would go on a slight incline, the car would hit a "flat" spot and would hesitate. It wouldn't do this all the time though. Once I got back on a level surface, it would pick back up and be fine. It seemed to happen when the fuel shifted in the tank. The other day, I came to a stop, started to go again and that was it! I can't even drive it now. It will start and idle fine but it also won't go over 4k RPM. I did a tune up as well as drop the tank to inspect the fuel pump. The only thing I can add is that mine is "Burping" through the air filter. Also, if I let it sit for a day, it starts very hard. I'm tearing into it again today and will update if I have any luck!

[nick0750]

does sound as though you cat is plugged you vehicle is a 2001 you should be under 80,000 miles which may be covered by federal emmisions warranty you should visit your local pontiac dealer.

[JITTI]

man i have the same problem i bought a obd2 scanner says multiple misfire p0300 and i am pretty sure its the cat converter because i changed the wires the egr valve because it did say it was that and everything but if u get yours fixed before mine please respond and tell me thanx and i will do the same!

[kilroypr]

You have covered your bases. Check the timing belt and the cat converter

[nick0750]

this vehicle doesnt have a timing belt, they have a chain.

[MCSSPORT]

My problem turned out to be the fuel pump. New pump and 2 hours later she fired right up and runs better than ever. Well, I'm off to the next project!

[JITTI]

i really think its the cat converter i am gonna get on it in the next couple of days i will let u all know what happens thanks for all of your help!

[stra8uphoosier]

I have a 93 GP and when i hit the accelerator it starts jerking until i get to a decent speed then when i let go to slow down it does it again so I took mine to the dealer and they said its the ECM and that its loosing memory so that might be it