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Pontiac Grand Prix Repair Questions and Answers

Question: 2001 Pontiac Grand Prix  mileage: 120,000. My car recently quit running I took it to the shop and they told me it was the fuel injectors I needed to replace all 6. And a thousand dollars later the car runs but not good. Can you tell me what else I should have looked for?

Answer: First of all, if a major tune-up has not been done within the last 2 or 3 years, you need to do it now. Scan the computer for fault codes to locate a malfunctioning component if there is one. Check fuel pump pressure; you may have a faulty fuel pump regulator or pump and filter.

Question: 2000 Pontiac Grand Prix GT, 3800 with 53,000 miles. I have had a mechanic tell me that the intake manifold gasket has a history of failure and that my car is starting to show signs of the gasket failing due to white dust found on the manifold. I had another mechanic tell me that it was due to the orange antifreeze and if I do a complete flush and use the green antifreeze that the problem may not get worse because it is the orange antifreeze that is causing the problem (deteriorating the gasket). What do you think? I would like to get high miles out of this car (200,000) but if this is going to be a recurring problem, I need to think about replacing the car.

Answer: We have seen similar problems with cars that use the orange anti-freeze (coolant). To correct the problem, switch to green anti-freeze after flushing the system.

Question: 2002 Pontiac Grand Prix  mileage: 83,000. The car has an idle problem. It is somewhat intermittent. When first started it almost always idles well. When the engine is up to, half the normal operating temperature through normal temperature the idle becomes slightly rough. If the brake pedal is partially released and the car begins to move forward it feels jerky as if there is a miss, the car never stalls but sometimes the engine speed becomes erratic and it feels as if it lopes. The tach will fluctuate between 1200 and about 700 rpm when the car is idling at its worst (though it rarely gets that bad). When I pull away it accelerates smoothly and powerfully, at the next stoplight the idle is fine. After that, it usually happens all the time at a stop but rarely is the miss very pronounced, yet always present. Fuel pressure is fine the spark plugs are fairly new and not fouled. Also sometimes at cruising speeds of about 55 mph going up a hill in top gear {automatic w/overdrive trans) under light acceleration the sane kind of slightly jerky "miss" is felt. There are no trouble codes set ever. The engine does not burn any oil. It has a new catalytic converter.

Answer:   You may have a partially plugged fuel injector or low compression in one or more cylinders.

Question: 1993 Pontiac Grand Prix 3.1 mileage: 97,000. I have recently purchased this car. When I bought it I new it needed new rotors and pads. My wife and I drove the car home and the next morning I replace the rotors and pads. After replacing the parts, I noticed that when you push on the brakes the brake light comes on; the brake boost pump also actuates. Also when you are stopped at a light you can hear the pressure boost pump for the brakes actuating about every 3-10 second with the brake light coming on when the pump actuates. I bled the brakes three times but still no luck. Is it possible that I still have air in the line or could it be the pressure switch is bad?

Answer: If your car is equipped with an optional ABS brake system, the rotors that you purchased may be for a non-ABS equipped car. If so, this would cause the problems you are experiencing.

Question: 1999 Pontiac Grand Prix  mileage: 120,000. My car failed emissions testing with a high HC rating at high speed and idle. I changed the spark plugs, air filter, oil, and oil filter. When I returned for a retest, the high-speed passed with HC well below the standard. However, the HC rose from 363 ppm to 426 at idle, so it failed the second time as well. I've also noticed that sometimes when it starts, the engine will almost die, but then the choke kicks in and shoots the RPM up. It then seems to idle fine. Sometimes as well, when the transmission is in gear, the engine will oscillate and almost die, then speed back up to idle, then almost die, and so forth. Any ideas?

Answer: Scanning the ECM for fault codes will tell where the problem sensor is. There are hand help OBII scanners you buy and clear your own codes. Replace the O² sensor and check your catalytic converter.

Question: 1998 Pontiac Grand Prix 3.1 mileage: 109,000.  Recently replaced the rear disk brake calipers, rotors & pads and bled the complete system.  Brake pedal is pretty firm w/o engine running.  However, when the engine is running you have to press the brake pedal at least halfway to get any braking action & nearly to the floor before it stops.  It doesn't feel firm in my opinion.  What I fear may have happened is the master cylinder may have completely drained.  When I was replacing the first caliper I let the brake line dangle in a container to collect the dripping fluid.  Quite a bit of fluid (probably a pint) had drained out by the time I was ready to connect the brake line back up.  I left the brake line connected to the old caliper while I changed the other side.  When I was ready to bleed everything, I opened the bleeder fitting & let gravity fill the line & caliper.  Did this on both sides before using the typical two-person method to get the rest of the air out of the lines.  When I was not satisfied with the results after bleeding the rear calipers, I bled the front calipers, too.   What have I missed?  One last bit of information & question:  The rear calipers on this vehicle have an integrated emergency brake.  Is there any adjustment required to this mechanism that may cause this condition?  None of my manuals indicate it, but I was told they may need to be 'ratcheted up' by working the emergency brake levers on the calipers.  I tried activating the emergency brake countless times w/o getting a change in the pedal while the engine is running.

Answer:  There is a possibility that you still have some air in the brake system.  Also, check the rear emergency brake ratchet in the calipers.  Although they are supposed to be activated by pressing the parking brake pedal, we have found these ratchets have a tendency to hang-up and not adjust, as they should.

Question:  1994 Pontiac Grand Prix  mileage: 88,000.  About 2 weeks ago, I had the oil changed at a quick lube place.  Afterwards, I drove the car for about 70 miles with no incident.   The following day, on a short trip, I experienced loss of power and noted a spiking of the oil pressure, past the 80-psi mark on the gauge.  I drove another 2-3 blocks to a service station.  At this time, I noted large amounts of oil leaking out the bottom.  The manager of the quick lube shop came to investigate and found the car had no oil pressure.  They re-did the oil and filter and added engine protectant.  Within a day, the engine developed a rumbling noise; when warm, the engine had trouble maintaining oil pressure.  Work-up at my garage showed spun bearings and discolored rods from operating at high temperature.  We're currently negotiating with the shop.  They've offered an explanation, developed by the filter manufacturers association, that the car developed high oil pressure, probably due to a stuck oil regulator value, and blew the filter off the car; in other words, the problem was not related to the service.  This car has been well maintained and has no history of serious engine problems.  Search of technical service bulletins shows no history of high oil pressure problems with this engine.  The sticking points are no obvious sign of oil leak (or trailing oil) prior to the catastrophic oil leak and the spike in pressure I saw at the time of the leak.  I'd appreciate your comments regarding their explanations and any other insights.  Thanks!

Answer:  From what you have described, the only thing we can figure out is that the oil pressure relief valve stuck shut causing the oil pressure to rise.  With the increase in pressure, the oil filter failed.  The result, loss of all oil and rod bearing failure.  It is a very good idea when having an oil change to be sure that a major brand, high quality, oil filter is used, one that is designed for your type of engine.

Question:  1996 Pontiac Gran Prix  mileage: 31,000.  I have a general maintenance question.  I change my oil myself rather than going to an oil/lube shop.  Does my car have any grease fittings, which require periodic lube, or is everything sealed (lifetime lubricated)?  Thanks for your help.

Answer:  If you do not see any lube fittings, then you have a sealed unit.

Question:  1995 Pontiac Grand Prix  mileage: 116,800.  One day I was driving along when I shut the cruise control off. When I tried to use it afterwards it did not work and has never worked since.  I have checked the fuse, replaced the servo and the whole blinker switch assembly.  I am out of answers.  Do you have any advice?

Answer:  There is a switch on the brake pedal that may have gotten out of adjustment that could be causing your problem.

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