Cold car starts, idle speed is unstable, restart is normal, what's the situation ... unfold
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The idle speed is unstable when the cold car starts, and the hot car is normal. It may be that the additional air valve is not opened or the opening is too small when the cold car is started, which leads to the low idle speed of the engine and the unstable idle speed. Or when the engine is cold, the idle speed control valve fails and the opening is too small, so that the idle speed is too low when the engine is cold, resulting in unstable idle speed. Another reason may be that there is a problem with the quality of injected oil.
The cold car should be started at low temperature first, and the temperature in the engine is not enough. During cold start, more fuel should be injected to meet the power requirements. The larger the gap between spark plugs, the smaller the ignition energy. Fuel atomization is not good at low temperature, fuel needs high ignition energy, and the car has a long service life.
The ignition gap of spark plug is easy to become larger, which leads to the decrease of ignition energy, thus affecting the power performance and making the car shake. In addition, the aging of ignition coil, aging of spark plug high voltage line or leakage will also lead to the decrease of ignition energy.
There is an incorrect oil-gas mixture ratio in both open-loop and closed-loop control. If the automobile computer makes a mistake, it is the actuator that controls the oil-gas mixing and ignition time incorrectly, thus reducing the power output of the automobile and causing jitter. In addition to these faults mentioned above, there are other factors that can also cause the start-up jitter of automobile cold car, such as the fault of water temperature sensor and the difference of working conditions of each cylinder. These failures can't be solved by themselves, so you need to go to a professional repair shop or 4S.