What causes the car to shake when starting?

[McMadelyn]

The reasons why the car shakes when starting are: 1. Aging engine mounts; 2. Excessive carbon deposits on the throttle body; 3. Poor performance in one of the cylinders. The connection points between the car's engine and the frame are usually equipped with engine mounts, which can absorb vibrations, preventing them from being directly transmitted to the car body. Most engine mounts are made of rubber, and rubber products can age over time. When rubber engine mounts age, they become hard, which can cause the engine to shake during operation. The throttle body is known as the throat of the engine. When the accelerator pedal is pressed, the throttle opening increases, allowing more air to enter the cylinders, and the ECU then adjusts the fuel injection system to inject more fuel. If there are carbon deposits on the throttle body, the engine may experience unstable idling.