2001 Pontiac Grand Prix Really bad vibration

HAMILTON395

MEMBER
2001 PONTIAC GRAND PRIX
6 CYL
FWD
AUTOMATIC
160,000 MILES

The more you drive it the worse it gets. The whole car shakes like it is going to fall apart. I have changed the tires and it still does it. No one can figure out what it is. I have been told there is a little give in the cv axle but it only does it after you have drove it about 10-15 min. Or so. If you let off the accelerator it stops and when you get up to about 55 mph it stops. Any ideas on what could be wrong?

Tuesday, November 17th, 2009 AT 10:14 PM

1 Reply

KNOWYOURAUTO

MECHANIC
113 POSTS

You mentioned the cv axle has a little give, does the vehicle shake primarily under a moderate throttle above 20 mph?

Two possibilities:

1) Though someone else seems to have ruled this out, a bad cv axle inner joint will always show up under a moderate and heavy acceleration at speeds above 20mph. All the time. Letting off the pedal and coasting will stop the vibration. I understand that it the symptom is not present until after 10-15 minutes so here is another suggestion.

2) A misfire from the engine could also start after the engine is warmed up. Try power braking the vehicle when the problem is present.
A) Block the wheels, set the parking brake, place transmission in drive and press the gas pedal to no more than 1500rpm. If the condition is present in this instance the engine is misfiring.

Please post back with the details when you can.

Regards.

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Wednesday, November 18th, 2009 AT 5:30 PM