What Causes Engine Vibration at Idle?
2 Answers
There are several main reasons for engine vibration at idle: 1. Poor combustion in the cylinders: Insufficient combustion leads to inadequate power output, causing the vehicle to vibrate. 2. Low ignition energy: The primary issue during cold starts is low temperature. When the engine temperature is insufficient, both fuel and lubricant temperatures remain low, requiring additional fuel injection during cold starts to meet power demands. 3. Excessive spark plug gap: With prolonged use, the ignition gap of spark plugs tends to widen, resulting in decreased ignition energy. This affects engine performance and causes vehicle vibration.
I often help friends with car repairs, and engine idling vibration is a very common issue. Common causes include aging spark plugs that fail to ignite, causing the engine to misfire and shake violently; excessive carbon buildup in the throttle body blocking the air intake channel, leading to uneven air-fuel mixture; faulty mass airflow sensors providing inaccurate air measurements; weak fuel pumps or clogged fuel lines causing unstable fuel supply; and cracked engine mounts failing to secure the engine properly, transmitting vibrations into the cabin. My advice is not to delay—check basic components as soon as you notice vibrations. For example, spark plugs should generally be replaced every 20,000 kilometers, and the throttle body should be cleaned every 30,000 kilometers. Otherwise, prolonged issues can increase fuel consumption and emissions, and may even cause sudden stalling when parked, leading to accidents. Addressing the problem early at a repair shop can save you a lot of trouble.
