Why does a new car's engine shake when starting in winter?

[JoshuaRose]

New car engine shaking in winter can be attributed to the following reasons: 1. Low ignition energy causing vibration. When the engine temperature is too low, both fuel and lubricant temperatures drop. During cold starts, a richer air-fuel mixture is required, which in turn demands higher ignition energy. Excessive spark plug gaps or aging ignition coils/high-voltage coils can reduce ignition energy, resulting in engine shaking. 2. Incorrect air-fuel ratio causing vibration. During cold starts, certain engine sensors may produce significant signal errors, leading to ECU miscalculations. This results in inaccuracies in fuel injection timing and ignition timing control, manifesting as engine vibration. 3. Cylinder imbalance causing engine shake. In multi-cylinder engines, significant variations in ignition energy between cylinders may occur. Additionally, uneven wear of pistons and piston rings creates compression inconsistencies, causing uneven power output and subsequent engine vibration.