What are the reasons for severe shaking after the car starts?

[StJeffrey]

Reasons for severe shaking after the car starts: 1. Carbon deposits on the valves and intake ports; 2. Insufficient fuel in the cylinders and inadequate power output; 3. After prolonged use of the engine, the ignition gaps and timing control of the spark plugs in each cylinder vary, leading to reduced power; 4. Errors in the control of fuel-air mixture and ignition timing. The correct method to start a car is: 1. Insert the key and turn it to the ON position, at which point the vehicle is powered on; 2. All onboard computer chips and sensors receive power, taking approximately 6 to 10 seconds for all sensors to complete self-checks; 3. After all indicators turn off, turn the key to start the engine, following the normal starting procedure.