The air flow sensor is an important sensor of the intake system of the electronic injection engine. It is located on the intake passage between the air filter and the throttle valve. It can convert the air flow into a digital signal and provide it to the ECU to calculate the fuel injection amount. The injection engine mainly calculates the fuel injection amount by referring to the signals of the engine water temperature sensor, air flow sensor, intake pressure sensor, throttle position sensor, and air-fuel ratio sensor (front oxygen sensor).
The failure of the air flow sensor is generally divided into two cases: complete failure and abnormal signal. The former has no obvious external characteristics on the engine's influence, and it is not easy for people without experience to notice. The latter will cause obvious abnormalities in engine operation.
The control of the fuel injection quantity by the ECU does not entirely depend on the air flow meter, and there is corresponding control logic to respond to the failure in the ECU. Signal replacement. Therefore, the impact on the operation of the engine is not obvious at this time. For example, if you unplug the signal line of a working air flow sensor, basically the operation of the engine will not be affected. I have tried to unplug the air flow sensor when the engine is idling. At this time, the ECU cannot receive its signal, which is quite In the state of complete failure, the idle speed is not affected at this time, and the engine is also normal when the accelerator is depressed.
After the air flow sensor fails, the ECU can also be replaced with other reliable signals, and once the air flow meter data is abnormal, it will "deceive" the ECU, so it is easy to go wrong. Just like someone asking for directions, you can ask others to ask if you don’t tell others, and telling them a wrong path will definitely make him go the wrong way. The inaccurate signal of the air flow sensor will cause the ECU to make an error in the calculation of the fuel injection amount. This brings more problems, such as unstable idle speed, reduced power and increased fuel consumption.