Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!

Pontiac Bonneville General Maintenance and Repair



  • Hi,
    My 2002 Bonneville make a whining noise when I make a turn (left or right) AND accelerating at 20-40 mph. This noise sounds similar to a bad transmission gear noise.

    If I am coasting or braking when making a turn then there is no noise.

    Does anyone have any idea what this might be? Is this a serious problem that should be fixed immediately?
  • My 92 Bonnie (only 230,000 mi.) stalls after about 30 mins. running and won't restart until engine has cooled completely. It didn't set a code. I suspect either a crankshaft sensor or ignition module. Can anyone tell me if I'm on the right track and if so is there a way to test these individually. Thanks for any help I can get. p.s. Haven't checked fuel pressure yet but when it stalls it stalls dead and doesn't sputter.
  • There is nothing wrong with your boost gauge, or your supercharger. It is NOT causing a 'drain' on your engine. (Do not attempt to adjust your set. :shades: )

    Here's the secret: your boost gauge works on the same principle as a vacuum gauge on a non-supercharged engine. It measures pressure in the intake manifold, both negative (vacuum) and positive ("boost"). The only difference is that a vacuum gauge on a non-supercharged engine doesn't have a positive range. This makes sense, because the only way a non-boosted engine could generate positive pressure in the intake manifold is if you ran it backward.

    Any running engine is sucking air down its intake. If you can find a naturally aspirated car with a vacuum gauge and watch it (some cars in the 80s used to call them "economy gauges"), you will see it gives the same type of readings under the same conditions as your boost gauge. A vacuum gauge shows higher manifold vacuum (that's greater negative PSI) when the throttle is closed or the engine is decelerating. That's because the engine is pulling really hard to suck enough air through a tiny opening. To demonstrate, pucker your lips and inhale fast - watch your cheeks pull in with the negative pressure.

    Now try the same with your mouth wide open. This is what happens when you step on the gas - you open the throttle and the wider opening reduces the negative (vacuum) pressure in the manifold, because more air can now get in. This makes the gauge swing 'up' toward zero - but a vacuum gauge doesn't quite reach zero unless the engine stops running, because any time you're sucking any air this creates a manifold pressure that's lower than atmospheric pressure. (Tip: "Zero" on a vacuum or boost gauge = atmospheric pressure.)

    Again, the only difference on your car is that with a supercharger adding pressure to the intake manifold you will eventually get into positive PSI ("negative vacuum?") when the throttle is open wide enough, the load is high enough, and/or the revs are high enough.

    But even before the gauge swings above zero, your engine is getting the benefit of added air pressure and volume from the supercharger. More air down the intake = more fuel = more power. There is never a "drain" from your supercharger reflected on the boost gauge - it only shows the pressure of the air the car is inhaling. As a matter of fact, the extra "drag" imposed on the engine from having to spin the supercharger belt would actually be reflected in a slight INCREASE in boost on the gauge. (If that doesn't make sense read on.)

    The highest pressure that the stock supercharger on our cars is supposed to generate is 8psi - at that point a dump valve spits out the extra pressure before it turns our engines into giant grenades. If your gauge ever lingers in the red zone above + 8psi, it probably means you have a bad dump valve and you should fix it quick.

    Other than that, only two types of readings indicate engine trouble on a boost or vacuum gauge. (1) Vacuum not high enough at idle indicates a vacuum leak. Your gauge should be pegged in negative territory at idle. It might creep up a little when you put it in gear, and a bit more when you turn on the A/C. This reflects the load on the engine. (Get it? More engine effort = lower vacuum, and eventually positive boost if you have a blower.)

    (2) Erratic vacuum readings indicate rough running, like a cylinder missing its spark or leaking/mis-timed valves. I'm not talking about a gauge that swings wildly when you change throttle position - it's supposed to do that. I mean a needle that wobbles or jumps around, especially if you're not moving the throttle and the engine load is constant.

    That's about all I can add - your car sounds like it's fine. Hope this helps!

  • Where is the battery located in a 2003 bonneville?
  • hey, how/where do you find these codes? Is it something I can do without buying one of those expensive scanners?
  • alcanalcan Posts: 2,550
    A scanner or code reader is required. AutoZone will retrieve trouble codes no charge.
  • evandroevandro Posts: 1,108
    Under the rear seat, per the owner's manual.

    12-15 DEGREES(2X & 2 MONTHS APART),
  • I have a 1987 pontiac bonneville.
    My car is idleing rough. and it dies at stop lights. it feels like its not gettin gas. and when im driving it has no more acceleration. it used to be quick when i stepped on the gas. but now it hesitates. and i can hear the engine and the rpm but it doesnt even feel like its going anywhere. could it be a second fuel filter?
  • This morning I started my car, no problems. However, noticed that when I came to a stop or had to sit and idle in traffic my car started to shimmy. It shimmies from side to side, and the service engine light came on. Thinking maybe some built up carbon could be the issue, got some cleaner for the fuel system. That has yet to show an improvement. It hasn't stalled, and doesn't really act like it's going to. Just running rough. Acceleration is poor. Definately no significant change in the rpms. Recently changed spark plugs and cables. New battery too. Any advice would be great.
  • haropharop Posts: 59

    If you check my earlier message 1747, you may find it applicable to your problem. In fact, my Bonny 95 was idling rough but never died. I also felt it was not as quick as I was used to. But after 2 applications of Chevron-Techron fuel injector cleaner and switching to Chevron gas, my problems are gone.

  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,608
    >changed spark plugs and cables.

    I hope you used OEM quality wires and GM plugs. How many miles are on your car?

    You might check to be sure all your wires are still in place and connected.

    If you try the Techron, put in at nearly empty tank and fill up with number of gallons for the size bottle you bought-I don't remember the two sizes they have. They have an injector cleaner and they have a fuel system cleaner. You might look for the fuel system cleaner. Use premium brand name fuel.
    When down again if problem still there, repeat and fill up proper amount of premium fuel. Do not use again for a third time.

    Usually when I put it in, I notice a difference in 10 miles or so. It doesn't take using the whole tank to feel and hear an improvement.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • jgtmiljgtmil Posts: 19
    WOW you have given me more than enough info, I feel that I have been educated. This is why I use this forum, thank you.
  • jgtmiljgtmil Posts: 19
    I have a 95 bommy and everytime it rains my right rear floorboard gets flooded. This is while the vehicle sits. Part of the headliner is wet too it looks as if it is leaking from the moon roof but the seals look fine. Does anyone have any suggestion before my wires short out, we don't have the luxary of a garage...
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,608
    Aren't there drains tubes from the sunroof? Check those with a hose to see if they are carrying away water. I suspect one of those is backed up or leaking letting water get onto the headliner.

    Do the rear-facing drains come out in front of the rear wheels? I'm trying to remember what posters have said in other discussions.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • haropharop Posts: 59
    Exactly, and in my case I took off the plastic cover from rear-right and what noticed was the drain hose had come out and was loose. I just pushed it back and since then no more leaks for 4 years.
  • What are OEM cables? A mechanic friend of mine did all the work for free. I only supplied the money to get the needed materials.
    I was told not to drive it until after it was hooked up to a systems monitor to check out what the computer says.
    I did put in a fuel system cleaner. However, I have not driven 10 or more miles on it since then. Also have not been using premium fuel. (Little expensive for a teacher's salary)
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,608
    OEM is original equipment manufacturer.

    In other words, it's safest to stay with strictly GM wires or a true equivalent like NAPA's OEM. I think Belden makes an OEM level. I wouldn't put on the cheaper, hotrodder type wires that you may see or be pushed to buy at some auto parts stores.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

  • jgtmiljgtmil Posts: 19
    Is it possible that the drain hose has come loose from the moon roof side. I pulled the plastic cover and the back seat out to follow the drain and the tube seemed to be in the right spot. also there are water marks on the right side of the headliner, and i cannot find any way to remove the courtesy handles to get the liner off...
  • imidazol97imidazol97 Crossroads of America I70 & I75 Posts: 21,608
    I believe that's what post #1761 says. But I don't know how to get into there to check at the moonroof itself.

    I don't have sunroofs and never have since 1979 Mustang Pace Car.

    2015 Cruze 2LT, 2014 Malibu 2LT, 2008 Cobalt 2LT

Sign In or Register to comment.