Athletes need warm-up before competition, and cars need warm-up before driving. According to the coolant temperature of the engine, it can be divided into two states, which belong to the cold vehicle below 70 degrees, and belong to the hot car after 70 degrees Celsius. There are two common faults in cold cars: Idle Wobbling of cold cars and poor acceleration of cold cars. Many drivers are overwhelmed with these faults. The idle speed of the cold car is jitter. If the idle speed jitter of the cooling car coexists with the idling jitter of the hot car, the idle speed jitter of the hot car is first eliminated. Whether it belongs to the jitter should observe the swing of the engine tachometer pointer, or read the engine speed in the data block, because the engine cushion damage will also cause the engine idle jitter, especially when the automatic block is put into the forward gear. The causes of idle speed jitter are as follows: 1. Engine failure. For example, each cylinder pressure is uneven; 2, intake system failure, such as air intake pipe leakage. The intake valve and intake manifold are too much carbon, too much air in the throttle and intake pipe, etc., 3, engine management system failure. For example, water temperature, intake temperature signal is not correct, line failure, etc., 4, ignition system failure. For example, too much spark plug carbon or incorrect space, high voltage line, distributor cover leakage, ignition coil damage, etc. 5, oil supply system failure. For example, due to too much carbon in the nozzle, the nozzle is closed or blocked. Cold car acceleration is bad, although many auto manufacturers show that the cold car can start without preheating after starting, but I think a slight preheating of 3-5 minutes after the start of the engine is of great benefit, because this can reduce the mechanical wear and tear of the engine, and the small displacement car can make the engine power sufficient at the start. Cold car big gas door start is the wrong way of driving, at this time the acceleration car can be avoided, if the cold car slow refueling start to start the car is a fault. The reasons for the acceleration of the cold car are as follows: 1. For example, the low pressure of the cylinder leads to the decline of engine power, the more prominent in the state of the cold car, the excess of the intake valve and the overaccumulation of the intake pipe, and so on. 2, the intake valve and the intake pipe have overaccumulated carbon. The injected gasoline is absorbed by carbon and can not enter the combustion chamber; 3, the engine management system fails. For example, water temperature, intake temperature signal is not correct, line failure, etc., 4, ignition system failure. For example, too much spark plug carbon or incorrect space, high voltage line, distributor cover leakage, ignition coil damage, etc. 5, oil supply system failure. For example, due to too much carbon in the nozzle, the nozzle is closed or blocked.