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Pontiac Grand Prix: Problems & Solutions



  • cornellpinoycornellpinoy Posts: 196
    If you haven't already had this replaced, I would check the crankshaft position sensor. When this sensor goes bad, it causes the random stalling and start conditions you described. It happened to a family member's 3.8L and after this was replaced, the problem never repeated. Hope this helps.
  • jamie1022jamie1022 Posts: 6
    THANK YOU cornellpinoy! I noticed that prath20's message said that the car would stall out, but I don't have any problems with that. Is this still a possible solution for me. I don't me to sound elementary but I am completely lost when it comes to the mechanics of an automobile. One more thing, could this sensor explain why the starting issue has occurred only when I am at school, in the mountains of NC? While here I frequently park the car at an angled position. Just curious because I thought it was very odd that the problem never occurs when I am at home in Eastern NC where the land is flat. THANKS AGAIN!
  • Hey chiefs and chieftans,

    I'm having some recent trouble with my "baby".. she's a 2000 GTP with 110k.

    Trouble: For about the last 5,000 miles, she's been getting horrific gas mileage, about 50-60% of normal. Went from about 22 mpg average to about 12, and it worsens as time passes. Most recently, there's been some issues with accelleration, typically when the supercharger is engaged.

    Recently, I did a full maintenance round: new tires (Potenza RE950s), synthetic oil change, fuel line cleaning (looked like an IV drip), oil system cleaning, etc. All in the hopes that my mpg problem would go away and I could move on. Nope -- now the new problems have surfaced.

    Shifting problems, high revving before gear changes, and most recently, if the supercharger is engaged, the meter goes up but rarely does down (like its 'stuck').
    Anyways, I'm at my wits end, and before I take it in, I want to go prepared and have some idea of what to say so I don't look like fresh bait to the dealer.

    Within the last 100 miles, the service has been gone. Right now, it looks like I'll be getting about 150 miles on this recent tank since the maintenance round. I used to get 400 on a tank. With gas prices being what they are, you can see my frustration. I keep thinking that its "cleaning itself out" and just to give it time, but I also don't want to make anything worse!

    History: At 8,000, tranny went bad, GM replaced 100%. OEM tires lasted for 70,000 miles (dont ask, I dont know!!), regular oil changes, regular service updates, etc. 2nd battery, new climate control deck (that went bad) and due to some hub/sensor issue, I've driven for a long time with no ABS or TCS. (If anyone has a suggestion on getting that turned back on, let me know -- I'd love to have it back but not for $600 to replace the hub).. now at 110,000, looks good, has run OK up until the last 5k. She's been a trooper, for sure.

    Any help would be appreciated tremendously.

    Richard Riga
  • tripntripn Posts: 2
    What are indications of needing a catalayt converter? My engine light will not seem to go off. I am not losing power, or smoking. The place I get my oil changes has told me I needed oxygen sensors and I fixed them.
    also can a catalayt converter make your engine get so hot to a 275 degrees? and possible blow a hole in your engine?
    Thanks for any help I can get.
  • worleyguyworleyguy Posts: 8

    Three things I didn't see mentioned in your message, O2 sensor, catalytic convertor, and timing. You can get an O2 sensor from parts store if your lucky, some emissions stuff you've got to get at dealer. It's easy to install. The converter my be gone, do you hear rattling from it? Back pressure and or bad readings at the O2 sensor may cause you to use more fuel than needed, but you would have noticed high revs, almost red line before changing gears. Also, timing, most expensive I think. If you have a belt like most cars today, not a chain, sometimes they will slip a cog or two. My dad had one slip, car had no power, none, reset the timing and got more power and gas mileage.

    good luck
  • worleyguyworleyguy Posts: 8
    Hello Cornellpinoy,

    I read your reply to Prath20 & Jamie.

    I would like to know, if you don't mind, how much that costs you?
    Also, did you look into it being the O2 sensor or the converter?

    Just curious, have a co-worker with this problem.
    He took it to a "Reputable Shop" and gave him a new battery and alternator for $450. I told him next time he wants to do that to one of his cars, I'd do it for $450 and I'd come to him.

    Anyway, he's got the same mileage and it sounds like he has the same issue as Prath and Jamie.

  • cornellpinoycornellpinoy Posts: 196
    Jamie - If your Grand Prix does not stall, replacing the crankshaft position sensor only may not solve your problem. If the car won't start only when its parked on an incline, its probably something else. How do you get the car to start when this happens?
  • cornellpinoycornellpinoy Posts: 196
    Worleyguy - The car was taken to a dealer and I just pulled the paperwork. Their diagnosis was a faulty crankshaft position sensor and bad electronic ignition module.

    When we had this problem, the car had 81K miles. I don't think the 02 sensor or catalytic converter was causing the random stalling and starting problem. It now has 151K miles and still has the original O2 sensor and catalytic converter.

    The crankshaft position sensor was $40, the ignition module was $140. The labor was rather high, but again, it was repaired at a dealership.

    And I agree with you - $450 for a battery and alternator is pretty steep!

    Hope this helps.
  • I have a 2001 grand prix, same problem, I have to tilt the steering wheel all the way up. Then under the steering colum on the right side below the ignition, there is a small slot that you can put your finger in. When you try and turn the ignition key, there is a small cylinder here that trys to ingage. If you fiddle with the cylinder while trying to turn the key it will release, Just try it a few times. GM in Canada wanted about $600.00 to fix the problem even though they knew about it since 1997. Good luck!
  • the check engine said that the rear o2 sensor needed replaced. It was replaced and the car is still making a bellowing noise that is continous after 15mph. i have noticed that when a steer left or veer left that the car does not make that deep bellowing sound. any suggestions?
  • fletcher4fletcher4 Posts: 1
    Well I own a Pontiac Grand Prix 99 v6 3800 series and i had the same problem as described above. My car had 81k though and only cost 3000 compared to yours. I will stay away from Pontiac after this. And yes, I tried contacting Ponitac and also they said pretty much go get bent.
  • jpark1jpark1 Posts: 1
    Did you find a solution to his problem. I have something similar. Tranny has been worked on numerous times, but when temp gets to 210, it drops out of overdrive, starts jerky shifting. After car cools down again, it performs normally. Tranny guys are mystified.
  • tripntripn Posts: 2
    coolant for my grand prix? I hear that it cannot be exposed to air? anybody know any truth in that?
  • patrick12patrick12 Posts: 2
    I don't know where you live, but I live in Lloydminster and the exact same thing happened to me at the dealership here in town. We found a website that pointed the problem to be in the console shifter. They told us it was in the column, not the shifter. $500.00 later, the same problem existed. They changed the shifter column and all was well. They credited me the first $500 because WE told them the problem and brought the car back 8 times.....
  • redhawg69redhawg69 Posts: 2
    I just replaced the blower motor resistor on my 1999 Grand Prix - it is located behind the blower motor against the firewall. To make it easier to get to drop the blower motor out of the way - three screws and a cable clamp.
  • I have replaced both front wheel hubs (R-50000 miles, L-70000 miles). It sounds like the right is going again (115000 miles)

    Do I need to replace the entire hub? Sure seems like I should be able to do just the bearings.

    Otherwise, this is a great car.
  • tb1019tb1019 Posts: 5
    I'm having this very same problem with my '97 Grand Prix GT, except that my A/C is not working, either. Have any of you experienced an inoperable A/C with your blower motor resistor failure as well, or are these two separate problems?
  • tb1019tb1019 Posts: 5
    I think my right hub is going, too. What is a ballpark figure for getting this issue repaired?
  • It's an ugly bill, $300-$500.

    I am looking for a cheaper alternative.
  • patrick12patrick12 Posts: 2
    On Thursday, the ABS light as well as the traction control light came on. I had a shop in town check for codes and none came up. I told him from what I had found, the wiring to the sensors on the front is a problem source, which he was aware of. The light was off for a few blocks and came on again. The ABS acted up today (Friday) once and the light is still on. Any one on this site have the same problem?
  • jamie1022jamie1022 Posts: 6
    Hey cornellpinoy ... I have figured out that being on an incline or decline doesn't make a difference. It just randomly won't start. I had it towed to a shop last Wednesday and by Thursday they were calling me to let me know that it had been starting the entire time so they were unable to determine what the problem was. I had to go pick it up and it has worked fine again until today. It won't start again now? UGH! Should I take it to another shop? THANKS AGAIN!
  • donahmjdonahmj Posts: 2
    1999 GTP 140000 miles.
    have replace 02 sensor. other normal maintenance battery etc.

    Had a problem awhile back that involve a vacuum activated fuel control valve on front of engine. The problem is that is was pulling too much vacuum. I was getting a fuel to lean code. I replace the valve, the vacuum hose ( before I determined the problems was too much vacuum. I capped off the line and valve. runs fine with no engine light.

    Now I am having this race condition, and I think it might be related. Problem has be intermittent. Could be heat related I live in Texas? and so far no codes.
  • donahmjdonahmj Posts: 2
    Can't answer your question? but I have a 99 GTP and have been to 110 with plenty of petal left. I was on the highway trying to pass a bunch of cars that kept cutting me off. It was as smooth as glass. Anyway why do you need to go that fast.

    don't wreck your sweet ride.
  • onyx1onyx1 Posts: 2
    Has anyone experienced this problem? My 1999 GTP quits sporadically while driving without any prior indication. Specifically, while driving at any speed the car just stalls out..... However it starts back up once I pull over and put it in park. There are also times when I can feel the sputter of the engine like it is going to stall but if I it the gas a few times I can keep it running however the tac goes to zero and stops working until I restart the car. I have had it into the dealer twice and they can not find any codes being stored to narrow down the problem. Help!
  • onyx1onyx1 Posts: 2
    Has anyone experienced this problem? My 1999 GTP quits sporadically while driving without any prior indication. Specifically, while driving at any speed the car just stalls out..... However it starts back up once I pull over and put it in park. There are also times when I can feel the sputter of the engine like it is going to stall but if I it the gas a few times I can keep it running however the tac goes to zero and stops working until I restart the car. I have had it into the dealer twice and they can not find any codes being stored to narrow down the problem. Help!
  • bobcainbobcain Posts: 1
    Have the same problem!!!! A mech . told me to have the crank Angle sensor checked.(C.A.S) and that this is probably the problem.
  • Hello,
    I have a 99 Grand Prix GT that keeps stalling. From these Forums I've heard that the crank sensor can be faulty. What kinda job is this to change? is it something that i can do myself or should i take it to a garage and do it? I have some experiene with engines, but not a whole lot.

    I've also heard stories of guys having faulty starter solenoids. Could this be the problem?

  • My suggestion is for you to check out the IAC valve. It's located on the top and rear of your motor.
  • I have just finished about two months of troubleshooting the same issue. You may or may not be getting the Service Engine Soon light when you have this problem. The source of my trouble was the crankshaft sensor. This supplies the signal for the ignition and the tach to your Ignition Module and your PCM (PowerTrain Control Module)- i.e. Car computer) The paret can be had at AutoZone for around $25.00 and it takes a mechanic 1 to 1.5 hours to change. I went to a small town where I used to live and got a very good rate on the work ($61.00) and things are now fine. Be cautioned, however, if this has been going on a while, there is a VERY good chance your catalytic converter has been trashed because the ignition hasn't been right and a lot of fuel was dumped in there. I had to replace mine twice while I figured out what was wrong. I had three mechanics look at it and they recommended everything from the car computer to Ignition Module & Coil packs. I recommed for finding a cat for your car (mine was $150.00 shipped) it is a fairly simple task to replace it. Hope this helps
  • gtpguy1gtpguy1 Posts: 1
    I had the same symptoms with my 97 GTP @ 150,000 miles - it would start and than stall immediately in hot weather. It would sometimes start and run OK in cooler weather and than stop after driving when it got hot. Sometimes the car would run OK again after being allowed to cool off for 30 minutes. The problem got worse until I could not drive the car.

    After much parts changing and $$$ spent I discovered that the fuel pump electrical circuit has an .8 ohm power resistor that was going open intermittently at high temperature. I replaced the resistor with GM PN 88951182 ($40) and it fixed the problem.

    You can diagnose this problem yourself when the car won't run by disconnecting the resistor (it is in the right front wheel well) and jumping the mating connector with a paper clip. If the car runs with the jumper installed you will know that the resistor is the problem. However, the resistor and connector is hard to access so you may want to just
    go ahead and have it replaced now rather than wait for it to fail again so that a positive diagnosis can be confirmed.

    Good luck - hope it helps!
This discussion has been closed.