1998 GT will not go over 4k rpms

[a1cjr]

I have a 1998 grand prix gt.
When in park and I get the engine up to 4000 rpms it will not go any higher. It will make a cycling sound and go just below 4000 rpms then back up and down.

Anyone have any idea on what I can check out?

[BIG-L]

Thats called a rev limiter and all of our cars are set-up that way from the factory.

~Larry~

[94sportsedan]

Like it's a bad thing you can't rev your engine beyond 4000 rpms, when in park or neutral.

[axle182]

Why does the rev limiter only work every now and then. Ive had a problem where my 98 shudders when you accelerate from the lights, and has a very slow take off. if you keep your foot down, it sounds like it back fires, and to get it to go, u have to take your foot off and slowly apply it. Also when its doing this, if you put it in neutral, it wont go past 4000 RPM and does sound exactly like a rev limiter. But when the car is running fine, there is no rev limiter. I dont rev the $%^ out of it, but i can get it to rev past 4000 and up around 5000+ without any rev limit. Any ideas what is wrong? The acceleration problem occurs whenever it feels like it, and can be very dangerous, when crossing oncoming traffic! any ideas?

Originally Posted by BIG-L

Thats called a rev limiter and all of our cars are set-up that way from the factory.

~Larry~

[BNaylor]

Originally Posted by axle182

Why does the rev limiter only work every now and then. Ive had a problem where my 98 shudders when you accelerate from the lights, and has a very slow take off. if you keep your foot down, it sounds like it back fires, and to get it to go, u have to take your foot off and slowly apply it. Also when its doing this, if you put it in neutral, it wont go past 4000 RPM and does sound exactly like a rev limiter. But when the car is running fine, there is no rev limiter. I dont rev the $%^ out of it, but i can get it to rev past 4000 and up around 5000+ without any rev limit. Any ideas what is wrong? The acceleration problem occurs whenever it feels like it, and can be very dangerous, when crossing oncoming traffic! any ideas?

When you go to drive (out of park or neutral) the rev limiter control from the PCM is inhibited. After that a speed limiter takes over. The rev limiter cuts off the engine around 4000 rpms for safety.

In your case you have a problem with engine misfire, etc. How many miles are on your 98 GP? Could be spark plugs, wires, fuel filter, ignition coils, dirty of defective Mass Airflow Sensor (MAF) or a clogged CAT convertor. Depending on your mileage I would put the CAT convertor and MAF sensor at the top of the list.



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.

[axle182]

My 98 has done about 164k. ive had it for about 3 months now, had the oil done and replaced with Mobil 1, got a new air cleaner which im about to put in, and will also change out the spark plugs asap. It seems to do the mentioned problems whenever it wants. has nothing to do with fuel level, outside temp etc etc. Oh and i was saying that the rev limiter doesnt always engage when the car is in neutral. sometimes i can rev teh car past 4000rpm. What would be the result if the rev limiter was engaged when driving? my understanding of the rev limiter, was that you wouldnt notice it at all until it actually got to 4000 rpm.when mine is playing up, it does it in low revs, so im starting to guess its nothing to do with the rev limiter. Any other ways of checking the MAF or the cat converter myself? Ive heard if i go for a long drive, i can check under the car and see if the cat is glowing. if it is, its blocked? Thanks for your replies

[BNaylor]

Here's a GP forum link to a DIY procedure I had posted in the past to check for clogged CAT convertor:

http://www.automotiveforums.com/vbul...=cat+convertor

On the MAF sensor, all you need to do to illiminate it as a possibility is disconnect it. Undo the electrical connector and take it out for a test run. The PCM switches to pre-programmed RPM values and mapping to control fuel injector pulse width. The idle may be a little erratic initially when you perform this test and you may get an SES light. If the symptoms change or improve, its the MAF sensor, if not just re-connect and continue on. The MAF sensor is located on the top of the throttle body. The small black module.

Good luck!




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.