Why does the vehicle shake severely during cold start?

[Henderson]

The main reasons for severe shaking during cold start of a vehicle are: 1. In low-temperature environments, the engine's internal temperature is insufficient. Therefore, more fuel injection is required during cold start to meet power demands. However, larger spark plug gaps result in smaller ignition energy. Poor fuel atomization at low temperatures requires higher ignition energy. Prolonged vehicle use can cause the spark plug gap to widen, leading to decreased ignition energy, which affects power performance and causes the vehicle to shake. 2. Ignition coil failure. The ignition coil is a transformer responsible for converting the vehicle's low-voltage current into high-voltage electricity, providing sufficient voltage for the spark plug to generate sparks. If the ignition coil fails, such as cracking or leaking electricity, it will result in insufficient or lack of spark plug ignition capability. Consequently, the air-fuel mixture in this cylinder will not combust properly, leading to engine misfire, difficult starting, and acceleration shaking.