1998 Pontiac Grand Prix GTP Supercharge from North America - Comments

Hello fellow Grand Prix Worshippers. The wife and I would be grateful for your help. We recently were offered a 1999 Grand Prix GTP Supercharged 3800 with 99,000 miles on it. We just love the performance of the engine as well as the style and interior. The question that we have is that sometimes when we are driving up a hill or in another situation where the car is shifting and is in the 35 to 45 mph range, you can notice the tachometer fluctuating slightly and feel the car gently being a little hesitant. It happens just briefly then smooths out and goes back to normal. It doesn't do it every time and when we called a dealership mechanic, they claimed that it was called torque converter bog and of course that they would be happy to check it out for $90.00. Not fix it, just check it out. We read where this transmission might have problems with a pressure control solenoid in the transmission, but wondered if this could be the beginning of a serious problem. It was a dealership trade in so we are getting the car without a warranty and are very concerned. If anyone has any info on this problem, we would be so happy to here from you as we really love the car and for $4700.00, it's hard to pass up. Thanks for any help and thanks for your time.

Luckily, the dealership reprogrammed the computer and now it runs perfectly. All of the transmission shops said that it needed a torque converter and a rebuild and quoted me $1800.00. I love this car.

I own a 1999 Grand Prix "GTX" (rare edition modified and offered by SLP; the same company that offered the Trans-Am "Fire-Hawk" and Camaro "SS") and absolutely love it. The first time I took it to the local drag-strip and ran it, I knew I had a gem. Impressively fast and stunningly beautiful, a bunch of guys (mustang, camaro, gto owners, etc. all with high HP cars) congregated to my car when I returned to the staging area after a pass down the strip. They wanted to "see" what I had under the hood... AWESOME! Made my evening to say the least. However, as a disclaimer, I don't really take her to the strip any more because of the fact that front-wheel-drive automatics don't hold up well under EXTREME torque situations such as sudden acceleration from a dead stop (wish a manual, RWD model had been offered... (sigh) ). I've not had many problems with her the whole time that I've owned the car, since I maintain it quite regularly; better to tackle smaller issues before they become major, $$$ expenses!

For the guys who've had bad fortune with their rides, I feel for you. Nothing worse than owning a lemon (especially if its your only mode of transpo)

I've got a 98 GTP with nearly 120K miles on it, and have had nothing but problems with it for the past few years.

Both headlights have fallen off.

The steering rack went out (which they later recalled, but for some reason will not give me my money back because it wasn't recalled at the time my car stopped wanting to turn left).

The mass air flow sensor went bad.

A random wiring harness shorted, causing the computer to throw incorrect codes.

The backlights behind the temp. gauge and the right half of the steering wheel controls have gone out.

The alarm goes off randomly, but didn't go off when someone broke into the car.

Today it's in the shop with a broken water pump, leaking hoses, and a cracked drive belt. I will never buy another American car again.

Hey Everyone, I was searching around on the internet for some information on my current problems, so I thought I would provide some insight on my car:

1998 GTP with 141K, most of the miles past 90K have been highway miles- I bought it used in 2000 with only 23K. I've had only one issue, during the warranty period, of the car stalling while I was driving and it was due to a the fuel pump ballast failing (around 26,5K miles or so) - before my warranty was up- I got a few little things replaced.

I will say my car has been very well behaved and has been reliable, even to this day despite it's current problem.

At 100K, I took it in for an "overhaul" - new spark plugs, wiring, belts, pulleys, new supercharger pulley, water pump (developed a small leak at about 90K), and a few other little items. There was a slight oil leak, on the engine itself (never actually leaked to the ground) -- that has since stopped and no longer smell oil for at least a year (self-healing?).

Right now, it hesitates to start (you have to press the gas while starting) - so I'm lead to believe maybe a fuel-injection problem? And also, a rattle noise from the engine when I'm at a red light, but if you put the car in neutral, you can hardly hear it. It's coming from the top of the engine (more than likely the supercharger?). My car is scheduled to go in for maintenance tonight or tomorrow.

My 1999 GTP has 135,000 miles on it. I has been a good car. I had to have the passenger door fixed as one day in a heavy rain storm the passenger floorboard filled with water. I understand there is a plastic shield or deflector in the door that will fail and allow outside water to come in through the bottom of the door.

At about 130,000 the engine control module failed leaving the car dead in the water. While in the shop I had the tranny flushed, filled and given a new filter. Had the shop change the super charger oil. Had the valve cover gaskets replaced. And it turns out the pop-off valve was broken; had it replaced.

Here I am 5,000 miles later and I have a new problem. The car died twice in three days. It will restart right away and drive fine. Another, and differnt, problem is that the tach will fall to zero and the TCS Off light will come on, but the engine will continue to run smoothly. The tach will fail only during the summer when it is warm outside. The dealer checked it out today and says that the engine has only died for them once and they think it is either the control module again (at $400) or the computer. Unless they can get the engine to fail again a time or two, they cannot properly diagnose it. They do believe the two problems (engine dying & tach failing) are linked. Has anybody else experienced this problem? I love this car and I want to fix it right.

Also, is there a fix for the GM radio display going in and out (more out then in)?

One more issue, the external temperature reading is incorrect once the outside temp climbs above the low 70's F. Any idea what causes this? The dealer says it SHOULD be the climate control head unit.

To the person two posts up check the cam position sensor, my brothers 98 had a similar problem with starting and that's what it turned out to be (after being diagnosed first :/)

I have a 2001 GTP, purchased in 2002 with 18k miles. At 82k miles now, the engine is great, but trans has always been slow and soft shifting. Not worth modifying a FWD car for performance, but still enjoy its abundant torque when needed. Definitely most performance available in a sedan at initial cost IMHO. All fluids changed before recommended intervals.

Problems:

ABS/Traction control was activating under light braking. Turned out to be wheel speed sensor $400. Thought it might have just been the cable.

2 window regulators and a window switch $1100, ouch!

AC Fan resistor pack burned out.

Eats tie rod ends every 30k. These FWD cars that are front heavy seem to do that. Excellent overall performance, but with a significant number of repairs.

I own a 1998 GTP and I absolutely love the car. love the pickup, love the displays, all the features, the sound system, lovely! goes fast and purrs like a kitty! it even has 158k miles on it, too!

Now I know there's a bolt on the supercharger that you can tune it up and down (gas mileage vs performance, does anyone know where it is and what the procedure is to tune it?

I have been a Pontiac customer for over 47 years... Enjoyed the Fiero and Grand Prix the most. But over the past ten years, the cars have come with and developed far too problems.

Seems like a lot of cheap plastic materials, poor workmanship, poor service knowledge and diagnosis. Dealers are fixing things that shouldn't be fixed and taking two or three or four visits to actually correct the real problem. (I've lost confidence in their abilities and diagnostics and product knowledge.) They tell me the manufacturer doesn't make life easy for them either.

Recently my well cared-for 1997 Grand Prix with 100,000 miles decided to lose a head-light cover again, terminate the left driver window (switch or motor), radio volume controls work backwards sometime, transmission slipped away, gas gauge which was unreliable... fuel pump quit, rear bearing noise was actually bad tires, valve cover gaskets started leaking again, front left wheel bearings are complaining, air conditioning stopped, engine temperature suddenly starts running hotter than normal at times for some reason (after three flush and fill coolant replacements plus thermostats), shop suggested a gasket replacement (they are guessing it is the intake manifold, because it is a common problem), air bag light stays on, check tire pressure light comes on and off,...oh, boy...I'm afraid to drive it, because something else will break.

The last super reliable Pontiac I had was a 1987 Pontiac Grand Am... some regular servicing... never burned oil between oil changes... changed fluids, brakes, tires... the car was great, small, but great... then some body rust started showing and we went to the Transport.

I have test driven some recent Pontiacs and am extremely disappointed; brake shutter on a new vehicle, whistling noises in the transmission as it shifts gears, less space for comfort & cargo, performance and responsiveness of power train lacking, style, color, blind-spots, Yuck!!!

Oh, for the good old days of the GTO. (We couldn't buy one in Canada, GM didn't think our business was worth their product.)

Where are all the Pontiac customers going??? Toyota???

To the person that posted on June 14th - about the TCS light going off and the Tac dropping to Zero - Engine sputters a little and then resumes just fine.

What did you find out?? Would love to know! I have had this car in 2 times to get this fixed and they have "fixed" 2 other things, but the issue is still happening.

Service engine light goes on now - and the code they say is a Crank shaft sensor - they fixed that and code went away for about 2 days. If anyone has an idea I would love to know. Want this car to last another year. Mine is a 99 GTP and has been pretty good to me so far.

It turned out to be just the Cable at the Speedo Head, Dashboard End.

We have a 1998 GP/GT. Headlight leaked at 30,000, and transmission position indicator in dash was out for the drive position dealer fixed both at no charge.

Heater blower quit, but started working after bench testing, has worked since. Drivers window regulator failed, but again tested it out of the car and it started working has worked fine since.

Battery failed causing the alternator to fail at 70,000 a friend said you replace both at the same time on the GP. ALso replaced the serpentine idler pulley, good I did factory was plastic and dealer recommended replacement with new steel one. NOTE: the idler bolt is a left hand thread, I broke mine off with pipe on ratchet and had to order a GM replacement.

Factory tires (Goodyear) lasted 75,000, were noisy however, but got better mileage than new Michelin's. Front brakes at 70,000.

I have a current problem/question: After the battery/alternator replacement once in a while the car would not crank. It lights up when ya turn the key, but when the key is in the far right position where it should crank over it does not crank. This has been a intermittent problem, but now it has failed and will not start the car.

I read a post on a different site where it might be the tumblers in the ignition switch or linkage in the steering column. I hooked a test light on the starter and no juice when I turn the switch to the crank position.

Anybody seen this one??

I have a 98 GTP Daytona since new and now have 204,000+ miles on her with very minor problems. Had to replace the front wheel hubs a few times and the headlight covers once. Also replaced the driver side window control and the heater fan. Other than that it's still running like a champ.

I am at my wits end. I have a 1998 Pontiac Grand Prix GTP. I am having problems with the transmission. It has 177,000 miles on it, and now it is having a shifting problem between the 2nd and 3rd gear. The transmission is pulling down the road just fine, but it won't shift after 1st gear. I have been told the 2nd shifting module, or sylinoid is out, but no 2 people are telling me the same thing. Can anyone help me please??