help. car sputtering at wot.

[1gtp99]

im new to the whole grand prix world. the car pulls fine untill i hit wot. then it just sputters. it almost seems like its bouncing off a rev limiter.. i just bought the car today. it has 121k on it. i have no idea what goes bad on these or what to check for. any ideas. thanks

[1998xGTP]

SES light?

[1gtp99]

Nope. no light

[FuglyGTP]

bad throttle position sensor?? It's really easy to test it.

[FoSHO99]

check the plugs, note how they look when you replace them

[1gtp99]

how do you test it?

[Mikegotone'02]

I'll bet you've got some old plugs in there. Previous owner probably skipped the 100k maint. FYI since you're new the gp world doing plugs is going to be a pain, BUT it's not impossible. Maybe someone can post a writeup for you. If you want to just check the plugs first i would pull out 1 of the fronts and take a look. It's hard to explain to you what to look for so here's a couple charts... use this to diagnose. I can't tell if they're going to be to small to read or not but if you google image: "spark plug charts" this is what you'll get. Google FTW!!





EDIT: yea they're too small lol but at least you know what to look for when you google it.

[1gtp99]

another this is that the car only does it when its warm.. until it warms up it pulls hard all the way through.

[dmoney01]

whats WOT?

[FuglyGTP]

another this is that the car only does it when its warm.. until it warms up it pulls hard all the way through.

sounds like a sensor to me but im no mechanic

[1gtp99]

wide open throttle

[1gtp99]

thanks for all the input.. im gunna fool around and clean the maf and see if it makes any difference.. and then check to see if the cat is clogged

[redrunner]

When I first got mine it did the same thing it was the plugs and / or wires I changed both.

[mikroehl]

mine does the same i just replaced coil packs with MSD, New MSD wires, NGK plugs, I cleaned MAF still same problem I am working on finding issue currently.

[98GTPCALGARY]

mine was plug's and Wires.... the first wire I took off fell apart when i touched it. ha
The guy I bought the car from thought the S/C was crappen out... so I got the car dirt cheap! (yay me!)

[1gtp99]

haha good job.. i wish i coulda pulled something like that off.. but when i test drove the car it was cold and didnt sputter at all.. then on my way home after it warmed up i punched it and it started to sputter.

[BiggRiggs]

You may want to hook up a scan tool and scan for knock retard at WOT when the car is warmed up.
The knock sensors don't come on until the car is warmed up (I forget what temp exactly), and if the sensors are detecting knock it would pull timing and the restricted timing could possibly be causing the car to feel like it's bogging down. That would explain why it's fine when cold also, because if the knock sensors aren't on then the PCM won't pull timing.

Anyways, since the car is up there in miles, it's probably a good idea to do a general tune up.
I'd at least change: Plugs, wires, pcv valve, fuel filter, and air filter. Also do an oil change and spray the maf sensor with maf cleaner. Wouldn't be a bad idea to put some fuel system cleaner in the tank either.
All in all, that would only take you an hour or so, and wouldn't cost more than $100 in parts and materials. If the filters and plugs are pretty old then you will notice a bit of a difference. At the very least you would know that the basic maintenance is done, and keeping up on maintenance helps keep the car happy.
You also may want to consider changing the supercharger oil, changing the transmission fluid and filter, and flushing the coolant too. Doing the seafoam-through-the-brake-booster wouldn't hurt either.

Either way, I would scan the car and that could also give you some insight as to what is going on at WOT.
If you or a buddy has a tuner, or something along the lines of autotap then you can scan pretty much all of the engine parameters and make sure it's not doing something goofy when you gun the gas.

Good luck, and congratulations on the new car.
-Riggs.

[mikroehl]

found my problem.. I replaced the plugs again! this time i went with some 104's I think it was the ngk that were the problem.. I never gapped them when i installed them so maybe that was the reason anyways i am happy i hope you find ur problem

[1gtp99]

i found my problem also.. it was the plugs.. it had some autoline 605's with idk how many miles. but some of them had up to a .90 gap.. the electrode was almost gone hah.. im glad i changed them when i did.. now it runs amazing.. thanks for all the input..

[BiggRiggs]

glad you got it figured out.
-Riggs.