I have a miss I can't figure out

[00GTP4ME]

Bad TPS....?

[inafogg]

vacuum issue, cracked hose maybe, map sensor?????????????????????

[00GTP4ME]

I'll put a second on a vacuum leak as well...

[guitarfish]

AWWW CRAP !!!!

IT AIN'T FIXED!

The tech said the fuel filter was rusted so bad and when he got it off, he couldn't barely blow through it, it was so clogged. He said after replacing it it ran great and had much more power. Well, it's still chugging.

Q - do these things have lockup torque converters?

The issue is now most prevalent at faster speeds and half throttle, and it makes the car lunge forward and back. I actually shot a video of the tach going up and down a couple hundred RPMs ever second, but won't be able to post it until later.

Besides the fuel filter, he said he cleaned the throttle body by spraying in whatever they use for that. Back to the drawing board. HIT ME WITH SUGGESTIONS. I was thinking of taking each sensor out of the TB and cleaning them with TB safe cleaner.

Unless I find something, it'll have to go back.

[tblake]

How does it drive if you drive in 3 instead of D?

[guitarfish]

Well well, this is turning out to be quite the puzzle. My repair tech spent some more time with the car today, and while he did feel the same symptoms I described, he wasn't able to pinpoint it on anything definitely yet.

He feels it will likely be one of the following:
MAF sensor
Cranck or cam sensor
Cat Converter - (the factory CAT died at 80K, and now the car has 197K, so he feels it's a possibility)

Based on how it's acting, his gut tells him MAF sensor. I'm going to drive it some more and as it gets worse, hopefully it will be easier to pinpoint.

That's about it so far. Suggestions welcome!

[The_Mechanic_33]

Fuel pressure and volume?????????????

[guitarfish]

It's most noticable at quarter throttle. Punch it and it smooths right out. I think that eliminates fuel pressure. The MAF kinda makes sense, but I'm not going to spend $200 on a hunch.

[michtom]

Sounds like spark breaking down spark plug wires should measure <7k, or coil, all should be between 5k-8k

[guitarfish]

Well, the symptoms haven't changed with both old and new plugs and GM wires. And the tech did test them after I installed them, and says they're good. It is a puzzle. When you stomp on the pedal, it smooths right out and there's lots of power.

[guitarfish]

I know this is an old thread, but I wanted to provide an answer. Based on my mechanic suspecting it may be the MAF sensor, I unplugged the MAF sensor and the car ran great for a month.

I just put in a new (used actually) MAF sensor and after a couple days, so far so good. So, if anyone has an issue like this, try pulling the MAF and see if it helps.

[00GTP4ME]

Originally Posted by guitarfish

Current Grand Prix's
2008 GP - 81,000
2002 GT - 201,000

Former Grand Prix's
1994 GP SE - Flipped at 231,000
1997 GP GT - Traded at 134,000
1998 GP GT - Traded at 225,000

Man. Now there is a true Grand Prix fan.

[guitarfish]

Originally Posted by 00GTP4ME

Man. Now there is a true Grand Prix fan.

Yeah, that's me. My son has an '04 too. I'm still saddened that there will be no more Pontiac. Great division, but sadly, GM is run by idiots.

[tblake]

What ever ended up being the problem?

[Danny DeVille]

My guess is O2 sensor, Coil pack, or converter if you have a hissing noise when under a load.