Has anyone experienced this difficulty with a Grand AM. This vehicle has 86K miles. We have had all tires replaced balanced, alignment twice and control arms/bushings replaced. Our local Pontiac dealer cannot seem to diagnose why this vehicle shudders terribly above 60mph. Could it be the engine mounts or transmission? The dealer we went to has ruled out the suspension. Help!

 

The Oxygen Sensor I dont know if this could help or not...

Replacing a worn-out oxygen sensor will save you money.
Properly functioning oxygen sensors are important when it comes to your vehicle's fuel economy and exhaust emissions. That's why checking for, and possibly replacing, a worn-out oxygen sensor is an important part of every routine tune-up. Plus, properly functioning oxygen sensors are good for the environment, and can save you hundreds of dollars in gasoline costs over the life of the sensor.

A worn-out oxygen sensor:
[ul][*]Wastes fuel[*]Can cause engine performance problems, such as surging and hesitating[*]Is the number one cause of excessive harmful exhaust emissions[*]Accelerates catalytic converter damage[/ul]


Replacing a worn-out oxygen sensor:
[ul][*]Saves money in fuel costs[*]Improves engine performance[*]Reduces air pollution[*]Prevents premature failure of the catalytic converter[/ul]

 

From experience I have learned that if its OVER 60 it means that your tires are not speed balanced, or you may have a bad tire that has a bubble in it, or tread issues such as separation or something along those lines. Under 60 means bearings, alignment, ball joint issues....
Hope this help
Mike

 

oxygen sensor! or unbalanced tires? i had them both that and shuddering was a symptom

 

ok bud when you or the garage torqued your tires lug nuts make sure they or urself use a torque wrench and not over torque it . if your lug nutts were over torqued it might damage your rimm and once you go over a certain speed you can hear it . soo it mite not be the tires but the rim itself

hope it helps