99 pontiac grand am vibration?

[cgdicamillo]

I have a 99 pontiac grand am, when the vehicle is in the drive position it vibrates. we thought spark plugs, changed them, check the motor mounts, those were good. any suggestions/ideas to whats the cause?
it's only happening during an idle postion while its in drive, could it still be the rotors then??

 

[john m]

ok if you were slowing down from speed then i would say its the rotors but if your at a stand still and it shakes, first off what plugs did you get, never get anything other than ac delco plugs for that car. autolite champion and all those others work but they dont work as good as the oem parts. try the spark plug wires after that.try that first then get back at me

 

[john z]

rotors. One too many brake jobs without having them turned will cause vibration. As the brake pad lining deteriorates, it puts A LOT of heat on them, causing them to warp. Also, if the pads ever were completely gone, you could have warped them. I would check this out.

 

[geko007]

Mounts

I had the same exact problem. 2002 3.4. gt. put in drive at stop and vibration almost as a misfire. put in reverse goes away, while in reverse put hand brake on tight then put trans in neutral and goes away. while still in reverse and hand brake put back in park and nothing it goes away! when you put torque on the mounts in a certain position and then dont let the engine rock back to its "slacked" position meaning worn mount, then you do not feel it. Replace bad mounts and fixed. These engines always have had what feels as a small misfire but can be amplified if the engine is sitting on barely any rubber from the old mounts. Vibration travels through the engine cradle onto the body causing you to feel that "misfire" which is really a vibration.