What Causes Excessive Vibration at Idle Speed in a Car?
3 Answers
Here are the reasons for excessive vibration at idle speed in a car: 1. Ignition system issues: Check the working condition of spark plugs, high-voltage wires, and ignition coils. Poor ignition system performance or faulty spark plug firing can cause this type of problem. 2. Unstable fuel pressure: If you've already cleaned engine carbon deposits, throttle body, replaced gaskets and spark plugs, but still notice body vibration at idle, it's recommended to visit a 4S shop to inspect fuel supply pressure and intake pressure sensors. Abnormal fuel pump pressure or faulty intake pressure sensor readings can cause body vibration. 3. Aging engine components: Car vibration can also be related to worn engine mounts. Engine mounts act as the vibration absorption system for the engine, absorbing minor vibrations during operation. If engine mounts fail, these vibrations will transfer to the steering wheel and cabin, causing shaking at idle speed.
Excessive idle vibration is a common issue, primarily caused by engine imbalance. The most frequent reason is aging engine mounts, where the rubber bushings harden or crack over time, losing their damping effect and allowing engine vibrations to transfer directly to the vehicle body. Secondly, problems in the ignition system, such as worn spark plugs or faulty ignition coils, can cause misfiring in a cylinder, leading to uncoordinated operation. Another cause is excessive carbon buildup, particularly in the throttle body or fuel injectors, which disrupts the air-fuel mixture and results in unstable idle. Ignoring this issue can worsen the problem and even damage internal engine components, so it's best to have a comprehensive inspection at a repair shop promptly. Replacing worn parts or cleaning carbon deposits can alleviate the issue. Regular maintenance, such as checking mount conditions and periodically replacing spark plugs, can prevent recurring vibrations.
As an experienced driver who has driven various cars, I've personally encountered idle vibration issues. Once, my steering wheel buzzed and vibrated at idle, and upon inspection, it turned out the engine mount rubber had aged and cracked. After replacing the mount, the car became quiet again. It could also be caused by worn-out spark plugs leading to poor ignition and unstable engine operation, or a clogged air filter restricting airflow and affecting combustion efficiency. Severe idle vibration can also increase cabin noise and cause long-term wear on tires or other suspension components. I recommend regular observation - if vibrations suddenly worsen, prioritize checking if spark plugs are blackened or worn, and opt for reputable brands when replacing to avoid counterfeits. With proper maintenance, major issues are usually avoidable, but don't delay repairs as they affect driving comfort.
