Why Does a Car Shake at Idle?

[Judy]

Reasons for car shaking at idle: 1. Unstable oil pressure, abnormal fuel pump supply pressure, or incorrect readings and poor performance of the intake pressure sensor can cause body shaking; 2. Severe engine carbon buildup, dirty throttle body, or excessive carbon deposits in the fuel injectors; 3. Ignition system issues, poor ignition system performance, or faulty spark plug firing can also lead to such symptoms; 4. Aging engine components, engine mounts are responsible for absorbing minor vibrations during engine operation. If the engine mounts fail, these vibrations will be transmitted to the steering wheel and cabin, causing shaking at idle.

[VanRemington]

I've been driving for decades, and the most common cause of idle vibration is issues with the ignition system, such as aging spark plugs or damaged ignition coils causing certain cylinders to misfire, leading to unstable engine vibration. Clogged fuel injectors or unstable fuel pressure can also disrupt the air-fuel mixture ratio, affecting idle smoothness. Additionally, air leaks in the intake system, like a broken vacuum hose, can cause the computer to receive incorrect data and make improper adjustments. When the engine mount rubber ages, it can't absorb vibrations, making the shaking more noticeable. I recommend regularly checking spark plugs for carbon buildup and replacing or cleaning them promptly; periodically cleaning throttle body carbon deposits to ensure smooth airflow; and using higher-quality fuel to avoid injector clogging. Ignoring small issues can worsen vibrations, potentially increasing fuel consumption by up to 20%, ultimately harming engine lifespan.

[LeSavannah]

As a budget-conscious car owner, idle vibration is particularly annoying because it wastes fuel money for nothing. When the idle is unstable, fuel efficiency drops, and it's common to consume 10% more fuel. Common causes include a dirty mass airflow sensor sending inaccurate signals, or poor fuel quality causing uneven fuel injection from the nozzles, leading the ECU to incorrectly adjust the mixture to be too rich or too lean. Sensor issues like false readings from the oxygen sensor can also increase emissions and pollute the environment. I regularly clean the air filter and sensors to prevent dust buildup from affecting accuracy. I also fuel up at reputable gas stations to ensure fuel purity. Once fuel consumption improves, it can save a lot of expenses and reduce emissions.

[NovaDella]

Commuting for an hour every day, the idle vibration is really uncomfortable. The engine buzzing noise affects driving comfort. Usually, it's caused by excessive dirt on the throttle body or a faulty idle control valve, leading to uneven air intake and unstable vibration. Or, the engine mount may be loose, directly transmitting vibrations to the car body interior. Safety issues cannot be ignored. Severe vibration may cause sudden stalling at intersections, which is extremely dangerous. Early detection and repair can prevent hidden dangers from escalating into more serious faults, ensuring smooth driving.