The gas flow sensor is very useful for the gas test. In some cases, the gas flow sensor is used to judge whether the concentration of a certain gas is excessive. When using the gas flow sensor, we must clearly know whether the gas flow sensor is Normal work, if the fault can be judged, what are the common types of faults in the gas flow sensor?
The faults of the gas flow sensor are divided into two categories, one is that the signal is out of the specified range, indicating that the gas flow sensor has failed. Modern electronically controlled vehicles have fail-safe functions. When a sensor's signal fails, the electronic control unit (ECU) replaces it with a fixed value or replaces the signal with the faulty sensor with the signal of another sensor. After the gas flow sensor fails. The ECU replaces it with the signal from the throttle position sensor.
The other type is signal inaccuracy (ie, performance drift). The inaccuracy of the gas flow sensor signal may be more harmful than the absence of the signal. This is because. Since the signal does not exceed the specified range. The electronic control unit (ECU) will control the fuel injection according to this inaccurate air flow signal, so the mixed steam is often too thin or too rich. If there is no air flow signal, the ECU will use the signal of the throttle position sensor instead, and the engine idle speed is relatively stable.
With this feature, the performance can be judged by unplugging the gas flow sensor connector.
1 If the fault phenomenon has not changed, the gas flow sensor has been damaged. This is because the ECU has confirmed that the gas flow sensor has failed and has replaced it with a throttle position sensor signal. The result of the presence of the gas flow sensor at this time is the same, so the failure phenomenon does not change.
2 If the fault phenomenon is reduced, the performance of the gas flow sensor is changed, and the signal is biased. Since the air flow signal is within the effective range, the ECU controls the fuel injection amount according to the distorted signal, causing obvious malfunction. After the connector of the gas flow sensor is removed, the ECU considers that the gas flow sensor is completely invalid, and instead uses the signal of the throttle position sensor instead, so the working condition of the engine is improved.
3 If the fault phenomenon has deteriorated. The gas flow sensor is normal. This is because the ECU controls the fuel injection amount according to the normal gas flow sensor signal before the plug is removed. After the plug is removed, the ECU uses the throttle position sensor signal to control the fuel injection. Since the latter's control accuracy is not as high as the former, the fault phenomenon is deteriorated.
In addition, since the gas flow sensor signal is the main basis for controlling the air-fuel ratio, the infrared exhaust gas analyzer can be used to measure the engine idle condition and the exhaust gas composition at 2000 r/min stable condition. If the difference from the standard value is too large, it may be a malfunction caused by poor performance of the gas flow sensor.
Wenzhou Selection Technology Co., Ltd. , https://www.zj-packaging.com