Thread: 97 Grand Prix GT 3800 V6 Shakes When Shifting Into Overdrive

I have a 1997 Pontiac Grand Prix GT 3800 series that shakes when it shifts into overdrive. When driving, the car will bog down if I keep pushing down on the accelerator. If I left off of the accelerator and push back down it stops and the car is fine. It tends to do this mostly when going up hills. This problem only occurs every once in a while. I have noticed that the problem occurs more often when I buy gas from certain stations. I also noticed one day after about a 2 hour drive, that I could smell fumes, which was what smelled like gas. I've been told that this problem could be a number of things. At this point, it would be pointless to run through the car to fix everything that could be causing the problem. Is there anyway to single out, at the most, 2 options that are most likely the problem? The car has been doing this for a year now and I have just learned to live with it.

When was the last time a tune up was done (plugs/wires/fuel filter/air filter)?

The gas fume thing you might want to check out. Check all the fuel line connections under the hood for leaks as the conenctors are known to leak and could cause a fire.

The fuel filter and air filter have been changed recently. (Within the last 2 months) I have not changed the plugs or wires since I have owned the car which has been over a year. As for leaks, I always keep a check on all my fluids and haven't ever noticed any major leaks and the car doesn't leak fuel.

I've started to use gas that is tested to be ethanol free or higher octane. This seems to cut down on the problem but not eliminate it.

i have been having a similar issue for a while. I have changed a lot of items and recently i discovered that my MAP sesnor was broken. I have ordered one and hope it will fix my problem when i receive it tuesday. check all your sensors to see if any might be broken.