Most Likely Causes:
* Engine Mounts: Worn or broken engine mounts allow the engine to move excessively, causing vibrations to transfer to the chassis. This is a common cause of shaking, especially during acceleration. Inspect the mounts visually for cracks or excessive movement.
* Transmission Problems: Issues within the transmission, such as worn-out internal components or low transmission fluid, can lead to shaking during acceleration. Check the transmission fluid level and condition. A slipping transmission is a strong indicator.
* Driveshaft Problems: A worn or unbalanced driveshaft can cause vibrations, particularly noticeable during acceleration. This requires a visual inspection and potentially balancing or replacement.
* Uneven Tire Wear or Balance: Uneven tire wear or improper balancing can create vibrations that worsen under acceleration. Rotate your tires and have them balanced. Check for worn or damaged tires.
* Spark Plugs and Ignition System: Faulty spark plugs or other ignition system components can cause misfires, leading to shaking, especially during acceleration. Inspect and replace spark plugs if necessary. Consider checking the ignition coil(s) and wires as well.
Less Likely, But Possible Causes:
* Wheel Bearings: Worn wheel bearings can create vibrations, but these are usually more noticeable at higher speeds than during just acceleration.
* Brake Issues: While less likely to cause shaking *only* during acceleration, warped rotors or sticking calipers can contribute to vibrations.
* Exhaust System Problems: A loose or damaged exhaust system can create vibrations, but these are often accompanied by loud noises.
Troubleshooting Steps:
1. Check fluids: Start by checking your engine oil, transmission fluid, and power steering fluid levels. Low levels can indicate a leak and contribute to problems.
2. Visual Inspection: Look carefully at your engine mounts, driveshaft, tires, and exhaust system for any obvious signs of damage or wear.
3. Test Drive: Pay close attention to when the shaking occurs (at a specific RPM, speed, or only under load). This information is crucial for diagnosis.
4. Professional Diagnosis: If you can't pinpoint the cause, take your Grand Prix to a trusted mechanic for a professional diagnosis. They have the tools and experience to identify the problem accurately.
Safety Note: If the shaking is severe, it's best to avoid driving the vehicle until it's diagnosed and repaired to prevent further damage or an accident.
