A modern car is a complex device equipped with a variety of automatic devices that allow you to adjust significant parameters that affect the operation of individual components and assemblies. These devices include mass air flow sensors designed to estimate the amount of air mixture entering the engine. They are usually used in combination with temperature and atmospheric pressure sensors. Various techniques and methods are used to test sensors.
Instructions
Step 1
Begin checking the air flow sensor by visually inspecting the duct to make sure there are no cracks or other defects. The air duct where the sensor is mounted must not have significant leaks.
Step 2
Determine what type of air flow sensors are used in your vehicle. This can be a device with a damper, with a heated film or wire, as well as a vortex type sensor. Depending on the type of device, select a method for checking it.
Step 3
To test a sensor equipped with a damper, connect the negative lead to the motor housing. Locate the ground, signal, and power pins in the air flow sensor connector. Connect the positive lead of the voltmeter to the signal terminal of the sensor.
Step 4
Remove the air duct and air cleaner cover to facilitate access to the damper. Turn the sensor flap several times (it should rotate smoothly, without tension).
Step 5
Switch on the ignition without starting the engine. Note what the voltage on the voltmeter is. It should be in the range from 0.2V to 0.3V. Now open and close the sensor shutter two or three times. With a working sensor, the voltage will gradually rise to about 4.5V.
Step 6
Reinstall the duct. Start the engine at idle speed. The voltage should not exceed 1.5V. With an increase in revolutions to 3000 per minute, the voltage should increase to 2.5V. Close the throttle fully. With a working sensor, the voltage should be higher than 3.0V.
Step 7
To test the sensor with a hot wire (film), turn on the ignition and make sure that the voltage is approximately 1.4-1.5V. Start the engine. At idle, the voltmeter should show a value of about 2.0V. Quickly open and close the throttle valve several times. In this case, the voltage should not change significantly.
Step 8
Begin testing a vortex sensor by identifying its signal contact. In idle mode, the signal frequency should not exceed 33Hz. Moreover, as the number of revolutions increases, the frequency should also increase. Now determine the voltage at the ground pin. If the voltage is not higher than 0.2V, the sensor can be considered serviceable.
