Why does the car shake severely at idle?

[LeBraxton]

Here are the possible reasons why the car shakes severely at idle: 1. Severe engine carbon deposits: It may be caused by excessive carbon deposits inside the engine, making it difficult to start the vehicle and causing idle shaking. 2. Ignition system failure: Problems with the vehicle's ignition system require checking the spark plugs and high-voltage wires. Abnormal operation of the ignition system can lead to this situation, resulting in idle shaking or difficulty starting. 3. Dirty throttle: Unstable fuel system pressure or malfunctioning fuel pump can prevent proper fuel supply to the engine, leading to poor fuel atomization or failure to open the injectors, causing cylinder misfire shaking or failure to start. 4. Engine cylinder malfunction: Insufficient cylinder pressure due to the engine exceeding its service life can result in intermittent idle shaking.

[DeclanLee]

The car shakes excessively at idle, mainly due to faults in some mechanical components. Worn or aged spark plugs in the ignition system can cause poor ignition, making the engine lose balance at low speeds and produce severe vibrations. The fuel system is also prone to issues, such as clogged fuel injectors or insufficient fuel pump pressure, leading to inadequate or uneven fuel mixture, resulting in pronounced shaking at idle. Additionally, aging or cracked engine mount rubber losing its damping effect can transmit vibrations directly to the car body. Carbon buildup in the intake system can also obstruct airflow, causing unstable engine operation. My own car had this issue before, and it was resolved after replacing the spark plugs and cleaning the throttle body. If not addressed promptly, the vibrations may accelerate wear on other components, increasing repair costs. It's recommended to regularly maintain and inspect these areas to prevent the shaking from worsening.

[DiVivian]

Severe idle shaking is usually caused by inadequate daily maintenance. After prolonged use, severe carbon buildup on spark plugs can prevent effective ignition, leading to irregular engine vibrations. A clogged fuel filter disrupts smooth fuel supply, causing unstable idling. Having driven many car models, I find that damaged engine mounts are a common culprit—they act like shock absorbers to dampen vibrations, but once they age, they fail. Additionally, leaks in the intake system or a dirty air filter cause unstable airflow, directly disrupting the air-fuel mixture ratio. Long-term neglect of these minor issues can worsen the shaking and even damage the transmission. Regularly cleaning the air filter and replacing spark plugs every two years can significantly reduce the chances of shaking, ensuring peace of mind and extending the car's lifespan.

[DakotaFitz]

Severe idle shaking is mostly caused by ignition system issues. Worn-out spark plugs or faulty ignition coils can lead to uneven firing among cylinders, causing engine imbalance and strong vibrations. Fuel system problems, such as clogged fuel injectors resulting in insufficient fuel supply, can also make the engine run unevenly. Additionally, worn engine mounts losing their damping effect can directly transmit vibrations. During repairs, I often encounter excessive carbon deposits affecting air intake, leading to idle shaking. For a quick check, listen for unusual noises during startup or check if any warning lights are on the dashboard. Address any issues as early as possible.