Why does the car shake violently when it is just started?

[DiLeila]

The reasons for severe shaking when the car is just started are poor fuel quality, carbon deposits in the engine valves and intake pipes, and spark plug failure. The specific reasons are as follows: Poor fuel quality: Inferior fuel has poor volatility. When the engine block temperature is low during a cold start, the fuel injected into the cylinders cannot mix sufficiently with air, resulting in difficulty starting and severe body shaking. Carbon deposits in engine valves and intake pipes: Carbon deposits can absorb an appropriate amount of fuel, causing the electronic control unit to misjudge, failing to provide the power needed for the car to start, leading to shaking. Spark plug failure: The gap between the spark plug electrodes gradually increases, reducing ignition energy and causing poor fuel atomization, which results in body shaking immediately after starting.