1.4 What's the reason for Yuefeng's idle shivering during cold start?

1. Low ignition energy leads to jitter. The engine temperature is too low, and the temperature of fuel and lubricating oil is very low. The cold car needs a thicker mixture and higher ignition energy when it is started. The gap of spark plug is too large, and the aging of ignition coil and high voltage coil will lead to the decrease of ignition energy and make the car tremble. 2. Incorrect mixing ratio will lead to jitter. When the cold car is started, due to the large error in the signals of individual engine sensors or some sensors, the ECU makes a wrong judgment and controls the ignition time through the fuel injection time of the actuator, which leads to engine jitter. 3. Engine jitter caused by different working conditions of each cylinder. The ignition energy of each cylinder of multi-cylinder engine is quite different. Because of the different wear degree of piston and piston ring, the compression ratio is inconsistent, which leads to uneven engine power output and engine jitter. 4. Engine jitter caused by other factors, such as incorrect air flow meter signal, poor exhaust gas recirculation valve or control system, unclean idle motor and bypass air inlet, poor fuel quality, and failure to reach the required calorific value, however, engine jitter occurs.