Hi there,

I was just wondering if anyone has experienced the same problem as I do. And if you could help me, I would sincerely appreciated it as I’ve tried almost everything, but to no result.

I presently own a 1998 Grand Prix SE with approximately 125K miles on it, and of late, I have been experiencing an ON OFF bout of jerky acceleration. When I accelerate normally, the car will sometime experience a brief drop of RPM before recovering again. This will happens at random RPMs, anywhere from 2000 to 3000.

This is what I have done so far, and what I have found…. I can’t seem to troubleshoot the problem. So if anyone has suggestions I’m all ears.

Things I have done;
1. Changed Spark Plugs
2. Changed Spark Plug Cables
3. Check the Mass Air Flow Sensor, and it seems ok, no burnt diodes observed.
4. Added fuel injector cleaner into my fuel tank

The first two was done, hoping that it was just a case of misfiring due to old cables and plugs. The 4th was done, to hopefully clear up any clogged injectors. However since this is an ON OFF issue, I’m not sure if a faulty sensor is the cause of all this?

There is one more thing that might help. After changing all the spark plugs, I used the old spark plug cables and I tried troubleshooting each individual spark plug. This was done by removing the cables from the plug and connecting the cable running from the igniter coil to an external plug. I was hoping to see if there was a misfiring coil, or a plug that wasn’t firing at all. However the problem remained except for the middle cylinder of the rear row. When I disconnected this plug, the car ran smoothly. When I reconnected it, the problem re-occurred.

So I thought it was the middle igniter coil, as such I got it changed when the problem re-occurred. However after changing the supposedly faulty coil, the problem still persists. Is there anything else that is faulty along the line?

When this problem happens, there is no check engine light, and the problem also occurs when you step on the accelerator when the gear is at netural. So I don't think the Tranny is the problem.

I’m kinda of a fanatic at getting things to run smoothly, and I’m really interested in finding out the cause of this problem. Not only to solve this problem, but also to know more about cars… and how they work. As mentioned, any help is greatly appreciated.

Cheers,
Tantor

It might be helpful if you could tell us which engine you have.








http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Hi there,

I was just wondering if anyone has experienced the same problem as I do. And if you could help me, I would sincerely appreciated it as I’ve tried almost everything, but to no result.

I presently own a 1998 Grand Prix SE with approximately 125K miles on it, and of late, I have been experiencing an ON OFF bout of jerky acceleration. When I accelerate normally, the car will sometime experience a brief drop of RPM before recovering again. This will happens at random RPMs, anywhere from 2000 to 3000.

This is what I have done so far, and what I have found…. I can’t seem to troubleshoot the problem. So if anyone has suggestions I’m all ears.

Things I have done;
1. Changed Spark Plugs
2. Changed Spark Plug Cables
3. Check the Mass Air Flow Sensor, and it seems ok, no burnt diodes observed.
4. Added fuel injector cleaner into my fuel tank

The first two was done, hoping that it was just a case of misfiring due to old cables and plugs. The 4th was done, to hopefully clear up any clogged injectors. However since this is an ON OFF issue, I’m not sure if a faulty sensor is the cause of all this?

There is one more thing that might help. After changing all the spark plugs, I used the old spark plug cables and I tried troubleshooting each individual spark plug. This was done by removing the cables from the plug and connecting the cable running from the igniter coil to an external plug. I was hoping to see if there was a misfiring coil, or a plug that wasn’t firing at all. However the problem remained except for the middle cylinder of the rear row. When I disconnected this plug, the car ran smoothly. When I reconnected it, the problem re-occurred.

So I thought it was the middle igniter coil, as such I got it changed when the problem re-occurred. However after changing the supposedly faulty coil, the problem still persists. Is there anything else that is faulty along the line?

When this problem happens, there is no check engine light, and the problem also occurs when you step on the accelerator when the gear is at netural. So I don't think the Tranny is the problem.

I’m kinda of a fanatic at getting things to run smoothly, and I’m really interested in finding out the cause of this problem. Not only to solve this problem, but also to know more about cars… and how they work. As mentioned, any help is greatly appreciated.

Cheers,
Tantor


My 95 was doing that and it turned out to be my fuel pump and filter needed to be changed. To much cheap gas for too long I guess (previous owner more then likely because it started doing it to me 2 days after I got it)

It might be helpful if you could tell us which engine you have.


Opps, sorry. It's a 3.1 litre V6 engine. I'm sure appreciative of the help. Cheers.

My 95 was doing that and it turned out to be my fuel pump and filter needed to be changed. To much cheap gas for too long I guess (previous owner more then likely because it started doing it to me 2 days after I got it)

Just wondering but when you mean filter, do you mean the fuel filter or air filter? I'm guessing its the former. And with regards to the fuel pump, is it possible to can it DIY? Or a mechanic is necessary? Because to change the fuel pump on some models of cars, you need to drain out the whole fuel tank.... so if that is necessary, then a mechanic is needed. But thanks for the info.

By the way, was it an on off thing too? Or once it started, it didn't stop?

Cheers,
Tantor

The fuel pump replacement can be DIY but it is a PITA. In the trunk, middle area close to the rear seat is an access panel that can be removed. The carpeting has to be peeled back. No need to drop the whole fuel tank.

But before worrying about the fuel pump you should be able to check fuel pressure at the fuel injector rails on a 3.1. On the rear bank of cylinders FI rail towards the right hand side of the engine (passenger) look for a Shrader valve. Fuel pressure should read around 59 psi with vaccum to the fuel pressure regulator connected.








http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Are you sure about the access panel, 97 I had didn't have one. I hope you are right though because a relative is looking for help here. My pressure specs call for 40-47? Maybe the info I have is wrong?

The fuel pump replacement can be DIY but it is a PITA. In the trunk, middle area close to the rear seat is an access panel that can be removed. The carpeting has to be peeled back. No need to drop the whole fuel tank.

But before worrying about the fuel pump you should be able to check fuel pressure at the fuel injector rails on a 3.1. On the rear bank of cylinders FI rail towards the right hand side of the engine (passenger) look for a Shrader valve. Fuel pressure should read around 59 psi with vaccum to the fuel pressure regulator connected.

Thanks for the info. I've read about how to the fuel pump and I've done such a task before on another car... thankfully it has a similar system where the fuel pump is convinently located...

But I'll give the fuel pressure a check.... I'll get back to you as soon as possible. I'm hoping that the Shrader Valve has some sort of dial on it that gives the reading... otherwise, am I supposed to buy some sort of equipment and reconnect the lines? Will check it out and get back to you all.

Cheers,
Tantor.

Are you sure about the access panel, 97 I had didn't have one. I hope you are right though because a relative is looking for help here. My pressure specs call for 40-47? Maybe the info I have is wrong?


Not 100% sure about the SE model but he can check. The '97 - '03 GT and GTP have the access panel. My GTP is a 97.5 and it has one. See link below:

http://www.automotiveforums.com/vbulletin/showthread.php?t=330940&highlight=fuel+pump+removal

On a Vin "M" 3.1 V6, the GM service manual calls for 41 - 47 psi but that's with vacuum connected at the fuel pressure regulator (FPR). I've seen it much higher though on 3.1 and 3.4 engines, especially with vaccum disconnected.

Have you tested the fuel injectors with a noid light or checked coil resistance on each injector solenoid.

BTW - Autozone has Actron fuel pressure testers with all fittings for around $30.00.

*Final note: In 1998 the fuel pump was changed on the 3.1 and is the same as the 3800 NA.




http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

hi I am having the same problem except it doesn't happen in neutral and it is intermittent no check engine light but I do have codes. on some occasions it is electrical solenoid a and sometimes electrical solenoid b both are tranny codes so i changed fluid and filter helped for a minute but came back any other suggestions 2000 grand prix gt 3.1

hi I am having the same problem except it doesn't happen in neutral and it is intermittent no check engine light but I do have codes. on some occasions it is electrical solenoid a and sometimes electrical solenoid b both are tranny codes so i changed fluid and filter helped for a minute but came back any other suggestions 2000 grand prix gt 3.1

The shift solenoids? At this point in time it probably would not hurt to try either Sea Foam or Lubegard tranny additive. Nothing to lose.

Replacing the solenoids or valve body work is not really DIY and the components are hard to access on a 4T65E tranny. Good luck!







http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.