What are the reasons for a car constantly shaking?
2 Answers
Reasons for a car constantly shaking: 1. Severe engine carbon buildup: The most common cause of car shaking is a dirty throttle body or excessive carbon deposits in the fuel injectors. When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold start injector is largely absorbed by the carbon deposits, resulting in an overly lean air-fuel mixture during cold starts, making it difficult to start. In this situation, the car will only start easily once the carbon deposits have absorbed enough gasoline to become saturated. After starting, the gasoline adsorbed on the carbon deposits is sucked into the combustion chamber by the engine's vacuum, making the air-fuel mixture too rich. This fluctuation between lean and rich mixtures causes the engine to shake at idle after a cold start. The lower the temperature, the more fuel is needed for a cold start, and the presence of carbon deposits significantly affects the success of the cold start. 2. Ignition system issues: Check the condition of the spark plugs, high-voltage wires, and ignition coils. Poor performance of the ignition system or weak sparking from the spark plugs can also cause severe shaking during cold starts. 3. Unstable fuel pressure: If you have already cleaned the engine carbon deposits, throttle body, replaced gaskets, and spark plugs but still notice shaking at idle, it is recommended to visit a 4S shop to check the fuel supply pressure and the intake pressure sensor. Abnormal fuel pump pressure or incorrect readings and poor performance of the intake pressure sensor can both cause the car to shake. 4. Aging engine components: Car shaking can also be related to the aging of engine mounts (also known as engine mounts or cushions). Engine mounts act as the engine's shock absorption system, absorbing minor vibrations during operation. If the engine mounts are faulty, these vibrations will be transmitted to the steering wheel and the cabin, causing shaking at idle.
As a seasoned driver with ten years of experience, I've encountered car shaking several times, most commonly due to tire issues, such as uneven tire wear or improper inflation, which causes severe shaking at high speeds. Additionally, bent brake rotors or poor wheel axle balance can also trigger shaking, especially noticeable during sudden braking. Unstable engine ignition, like faulty spark plugs or insufficient fuel supply from the fuel pump, can cause the car to shake erratically at idle. Wear in the suspension system, such as ball joint wear, is more subtle but easier to notice when driving over bumpy roads. I remember one time when the shaking was so bad that the seat vibrated—it turned out to be an unbalanced driveshaft after inspection. Safety first: if you notice shaking, first check tire pressure and appearance. If it doesn't improve, get it checked by a professional shop as soon as possible. Don't underestimate it, as it may hide major risks.
