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Pontiac Grand Prix: Problems & Solutions



  • i was having the same problem. for everyone with this problem, check the release button on the shift knob, sometimes it doesnt fully engage and then the shifter does not lock. the car has a feature installed that prevents the key from being removed with out the car being locked in park. hopefully this helps
  • Don't ignore it. My son's 97 Grand Prix did this, we checked the manual and read that it might be a problem with the quality of the gas and that we might need to run a couple of tanks through, short story, the next day it began to make a racket while he was driving it, it was towed to the shop and now we're told--you need a new engine....this on a car that had been serviced less than 300 miles earlier by the dealer and checked for everything that could go wrong as he was about to drive it to college. :sick:

    sad mom....and even sadder son :lemon:
  • I have a 2000 Grand Prix GTP and driving down the road it will just die. It starts right back up, no problems and I'm on my way. It has done this 3 or 4 times now. No check engine lights. Any ideas?
  • bxdbxd Posts: 186
    Crankshaft position sensor quite likely. Especially if it does this more often once the engine is warmed up. But I have seen them do this, or even not start at all, when cold. Probably $40 in parts and $150 in labor.
  • bxdbxd Posts: 186
    Under what circumstances did it overheat? On highway, stop and go traffic, idling?

    Not shifting into overdrive on the highway could be something as simple as low tranny fluid. Have you checked that? Must be checked with engine warm but not hot (about 20 minutes of light driving is good) and engine idling in park.
  • bxdbxd Posts: 186
    Most likely not "major", but not a simple maintenance reminder either. The light coming on indicates the computer has found something wrong with an emissions related system.

    If you take it to a mechanic, they will hook it up to a OBD-II code scanner and find the system that is at fault for about $50. Then the fix itself could be something as cheap as spark plugs or as costly as EGR valve, etc.

    If you are good with cars, certain auto parts stores will scan the code for free and you can look online to see what the code means, and attempt to fix it yourself.
  • ryguy2ryguy2 Posts: 3
    It over heats in traffic, but runs much hotter than normal on the road. Also tends to be when it is over 90 and not when under. the trans fluid has been checked and is fine.
  • mmxermmxer Posts: 12
    If you dont want to pay go to auto zone they will scan it for free :P
  • dagod1dagod1 Posts: 1
    It just got a new head gasket, It is eating about 2 quarts of oil per week and not leaking anything. I need help fast
  • bxdbxd Posts: 186
    If you are sure all the air is out of the cooling system, and you've done a flush, then you can either try chemicals like the Prestone flush I mentioned a few posts above, or, bite the bullet and get a new radiator.

    Also consider the thermostat one last time. I've had one fail on me that was only a few months old.
  • Any way to test the sensor to see if it is bad?
  • n8ten97n8ten97 Posts: 3
    I go over a bump in the road and the car shakes real bad, even after ive been past the bump. What could be causing this?? Shocks/struts? And what would something like that cost me to fix or could I do this myself?? Would just changing the strut cartridges work??
  • bxdbxd Posts: 186
    I assume you are asking, is there any easy way to test it at home, because if you have a scan tool, you can plug it in and watch for RPM as you crank the car.

    At home, here are some things to try:
    - As you try to start the car, does the tach show anything?
    - Do you have spark on any cylinder? If you do, it's not the CPS. If no cylinder has spark, you still can't say it's definitely the CPS because it could be the ignition module or ECM. Maybe even ignition coils but it's very unlikely all 3 pairs of coils would go bad at once.
    - If you don't have a scan tool but you have a scope or multimeter I think you can get a reading off the sensor wiring itself, BUT this is an undocumented way to test, so be careful. If you can probe the wires while someone else cranks I'd expect to see some kind of fast pulsing signal. Probably too fast for a multimeter.
  • bxdbxd Posts: 186
    Any noises along with the shakes?

    I would have a friend drive beside you on each side, and behind you, on a bumpy road. He should watch to see if your wheels after hitting a bump, settle right down or if they continue to bounce a few times. Have him watch all four corners, one at a time as they hit a bump at speed, at least 25mph.

    Bounces mean struts. On a 1996 it's a pretty easy job if you are mechanical. Try the test above and tell me what you learn. Also please share about any noises you hear when you hit the bump or afterwards.
  • alright, heres my story lol... sorry. I bought a 98 Grand Prix SE with 170,000km (i am canadian) used from a used car lot. I had the car 1-2 weeks and i noticed a minor tick, its not a knock! to it. Now the tick is weird heres why it ticks faster with the faster the engine rev's but if i go for a 15-20 minute drive the noise mostly goes away? I have contacted the car lot and they wern't willing to do anything for me (no warranty - not that the warranty would cover this anyways). I did an oil change with Lucas Heavy Duty Oil Treatment (mixed @ 20%) and yet nothing... So I took the car to the first mechanic (local) and he told me it was extremely difficult to tell where the noise (because of the echoing) was coming from but using the stethiscope he figured bottom end noise but not rods, checked bearing and there fine? so he told me that tearing it apart would be expensive and likely would result in a replacement anyway... so i was a lil disturbed and down got ahold of my fathers buddys who is also a mechanic (buy this time its got much louder) and he said the same about the echoing and he also had the stethiscope out and figured it might be lifters or just cylinder noise and I will have to replace the motor eventually. nothing thats going to cause me troubles for a little while. I was just wondering if anyone else has seen or heard of a similar situation? lol, unfortunitly i don't expect good news so don't hold back on a plus note i have noticed NO performance change? still lots of get up and go, no crumby fuel milage.

    Specs (just incase):
    1998 Grand Prix SE
    3.1 SFI Engine
    175,000km (not sure how many miles that is)

    thanks for reading, and thanks in advance for any information you guys can provide me with.
  • bxdbxd Posts: 186
    Sorry to say it, but "they all do that".

    There has been a 89 3.1 Regal, 97 3.1 Century, 97 Cutlass Supreme 3.1, 95 Cutlass Supreme 3.1, and 02 3.4 Alero in my family. All these engines are close relatives of yours, with the 97s being practically twins. :)

    The noise you hear is probably piston slap. It's a minor problem in these engines. My 95 3.1 has 152,000 MILES on it and ticks, but is running strong. Could be lifters too.

    I would not worry about it. Use good oil, do NOT use oil treatments, and change the oil every 4-5k miles and you'll be fine. If I were you, depending on how much Lucas you put in, I'd dump it and start over.

    If you want oil recommendations from me, tell me exactly where you live so I know the climate, and describe your typical drive (distance, speed, etc.).
  • momwagmomwag Posts: 14
    They all do that? That's a new one on me. Does it vary with RPM under driving load and in nuetral?

    If yes, it is likely to be piston slap. Quality oil will help. I suggest the Mobile 1 synthetic oil appropriate for your climate. I have a Sierra with 230,000 miles and a Grand Prix with 172,000 miles with strong engines and no piston slap. Never had internal problems on either. The secret is using synthetic oil and regular maintenance for the life of the engine.

    If no, it may be in the transmission which would cause the sound to appear in the bottom end of the motor if front wheel drive. Try a power flush and filter change on the transmission. When the oil heats up it flows easier around metal shavings that may be blocking the pick up and circulation points.
  • Well i am pretty sure its not a tanny problem... and after doing some research last night about this "Piston Slap" which conviently enough was brought up here, it seems to be a more logical explanation. is this something that would cost tons of money to have checked out? or even fixed? is it just a piston ring that needs to be replaced or would i have to re-bore? any extra information on this or sites would be greatly appreciated.

    for the oil information, I live in southern canada so its still bloody cold (well below freezing 10-20 fareinheit) in the winter and pretty warm in the summer (reaching 90-95 fareinheit. I live in a small town (very rarely city driven) and drive approx 40km (25miles i think?) to work.

    I did just do an oil change on this car and probably won't bother again untill my 4-5,000km are up. but thanks alot guys it seems everything is pointing towards this piston slap, just the way it acts. by the time i am home from work its running perfect. I was lead to believe that a lazy lifter or lifter troubles wouldn't go away when the car warms up.
  • momwagmomwag Posts: 14
    If the problem goes away after the engine is good and warm, your oil may be too thick for cold starts.
  • bxdbxd Posts: 186
    Perhaps "all" was a bit too strong, but I hear a tick/slap on startup on the MAJORITY of 3.1L / 3.4L (OHV, not the old DOHC one) engines.

    Sometimes very light, sometimes it goes on for a minute or two.

    Momwag, is your Grand Prix a 3.8 or 3.1? The 3.8s aren't as prone to this.

    Momwag is right about using the right oil.

    Southern Ontario isn't too different than my northern Ohio climate. If you can find Mobil 1 0W-40 I have had excellent results with it. Sometimes you gotta look around to find a store that sells it. It flows fast at cold temperatures and startup, yet stays slightly thicker at high temps than a 5W-30.

    If you just can't find 0W-40, go with Mobil 1 5W-30 in the winter, and in the summer 5W-30 but blend in 1/2 to 1 quart of the 15W-50 they have.

    Your mileage isn't extremely high but it's hardly a tight new engine either. Remember, when GM spec'd 5W-30 for your engine, they had dino oil in mind. A synthetic of the same "rating" will flow much better when you look at detailed manufacturer specs.

    As far as fixing it mechanically, I have no experience, but in all the online communities I participate in I haven't heard of anyone do it. Possible sure, but probably ridiculously expensive.
    Just remember that for the most part this is a benign noise you are hearing and good oil will keep the car running for many miles to come.
  • momwagmomwag Posts: 14
    I have a 3.8L. Great Car. I just wish they would get rid of the plastic parts on the window regulators.
  • sfc400sfc400 Posts: 2
    I know now that it is not the alternator and checked the fuel pressure which is in range.But the car still will not start.When I sprayed gas in the manifold the car started for just a moment any suggestions of what could be wrong.
  • bxdbxd Posts: 186
    If you spray starting fluid or gas into your intake and the car starts, you have a fuel problem.

    Is the fuel pressure gauge showing roughly 40psi both when you turn the ignition to "ON" and when you try to start the car? It shouldn't change much as you're cranking away, have a friend watch it for you as you try that.

    If you have good pressure, I would lean towards fuel injectors having gone bad. They are the last stop on the fuel's trip into the engine, more or less.

    But before you diagnose those, I would make sure you have good spark. Buy a spark tester and check at the front ignition wires that are convenient (one or two is fine). If you find spark (and I bet you will) then it's time to Ohm test the injectors... on that car I think you'd have to take the upper intake off to do so. You basically unclip each injector's wiring connector and check OHMS. You may find from 1 to a few of them deviating from the rest. Off the top of my head I can't remember the correct resistance but for some reason "12" is stuck in my head.... I will have to dig that up if you need it. Usually what I do is test all 6 and the 1 or 2 that are the most abnormal get replaced.
  • jwojwo Posts: 1
    I just want to note that Fuel injection cleaner only works on vehicles where the injectors are fairly clean or new. There are little filter baskets that are similar to a smaller version of a reusable coffee filter basket. If your injectors are really dirty all that will happen is that the chunks of grim and slug that the injector cleaner is cleaning off the insides of you rail and injectors get caught in these little baskets. Which will make your injectors spray worse and worse as the basket gets more and more clogged. If your injectors are really dirty I would suggest bringing them to get cleaned professionally by a Fuel Injection shop that has an ultrasonic cleaner. They will clean your injectors for $20/each injector and replace all the rings and filter basket for approx $5/each injector.
  • bxdbxd Posts: 186
    That's a good point. Once a car reaches a couple years of age, it's good to throw in a high quality fuel injector cleaner a couple times a year. Don't wait till there are problems. Chevron Techron is good, Gumout Regane is too. Skip the stuff that's 99 cents!! It's just alcohol. Anything that's just alcohol is a waste of money as almost all gas is 10% ethanol nowadays anyway.

    If you use a high detergency gasoline on a regular basis, that will cut down on the need for cleaners. Do a google on "top tier gasoline" to learn more.

    As far as professional fuel injector cleaning, it's not a bad idea, but GM injectors do fail electrically. It's common after 100k miles. So it's a better long term investment to replace them with new ones if you plan on keeping the car a while.
  • knepskiknepski Posts: 2
    Last year I hit a deer on the front passenger side. After the car was fixed and I picked it up the info center was dark. Initally I thought it wasn't working, but if it's light enough in the car you can still see the numbers and it is reading, it just somehow lost the ability to illuminate. I took off the dash and didn't see where anything is disconected. Anybody experienced this before?
  • bxdbxd Posts: 186
    I think the illumination for the display is LED based and almost assuredly built into the unit. Not a replaceable bulb really. I would go after the insurance on this if at all possible, it should have been covered.

    This is the only piece that lost illumination? Maybe it was coincidence that it went out from the crash.
  • momwagmomwag Posts: 14
    There is an image adjustment for the HUD that usually helps with ghosting. You might want to see if changing the settings helps. I am not sure if it effects brightness though.
  • dug2171dug2171 Posts: 1
    I have a 2000 GTP that started smoking from the dash as I was drove to work several days ago. I pulled over and was able to disconnect the battery after about 10-15 minutes. The car filled with smoke in the meantime. I had the car towed to a dealership that has now told me two wires under the driver seat were exposed and touched. Before I disconnected the battery it burned the wire harness, display harness and the fuse box (and possibly more). I received a quote of $1,600 for parts they have identified and at least a days worth of labor at $85/hour. I have contacted Pontiac who then talked to the dealer who basically told us to cut our losses and buy a new car. I contacted my insurance company who said it is not covered because it was a mechanical failure. Does anyone have a suggestion?
  • momwagmomwag Posts: 14
    Unless you can do the work yourself and get the harness from a junk yard you are going to pay more than the car is worth $$ wise. If the car is in good shape and you don't want to buy a new one it may be cheaper overall. How many other electrical components may have been damaged? You won't know until they fix what they know.
This discussion has been closed.