What Causes Engine Shaking and Stalling During Cold Starts?

[ElizabethMarie]

The reasons for engine shaking and stalling during cold starts include: carbon deposits in the engine, insufficient ignition energy, fuel supply line issues, and fuel quality problems. Carbon deposits in the engine typically manifest as deposits on the valves and intake passages. If these areas become carbon-fouled, they can cause the ECU to make incorrect judgments, resulting in insufficient fuel injection. Even if the air-fuel mixture burns completely, it cannot guarantee adequate power output, leading to inevitable shaking. In such cases, cleaning the throttle body can be a solution. However, prevention is key—avoid prolonged idling, occasionally drive at high speeds, and use reliable fuel cleaning additives. During cold starts, the temperatures of the engine, fuel, and lubricating oil are all low, requiring more fuel injection to meet power demands. Additionally, the larger the spark plug gap, the weaker the ignition energy becomes.