It seems that the car can't supply oil 2 seconds before the cold start in the morning, and it is normal after 2 seconds. What happened? ?

It's not that the oil is bad, nor that the throttle and throttle nozzle should be cleaned. The reason is that it is cold. We know it can only be started when it is cold. Because not all cylinders can start at the same time after adding rich mixture, if one cylinder starts later, three cylinders will work and then make a sudden noise. Because of the unbalanced power, cars with more than six cylinders will be better in this respect. This phenomenon usually appears in middle and low-grade four-cylinder vehicles.