General information
The hot-wire mass air flow sensor consists of a temperature-sensitive film sensor, a housing and a measuring channel (hybrid sensor element). The principle of measuring the mass air flow with this type of sensor is based on the fact that a change in the air flow flowing through the sensor causes a change in the amount of heat transferred from the surface of the element (films) film sensor to the air flow. As a result, the hot-wire sensor temperature changes and its resistance changes.
Based on the sensor signal, the engine control unit determines the required fuel supply (basic fuel injector open time) and ignition timing.
The mass air flow sensor generates pulses, sequentially opening and closing the circuit, which supplies power with a voltage of 5 V from the electronic engine control unit.
Type 1. | Type 2. |
Troubleshooting Guide
1. If the engine stalls occasionally, start the engine and try shaking the MAF sensor harness. If the engine stalls after this, check for a bad connection at the MAF sensor connector.
2. If the output signal of the mass air flow sensor is registered. different from zero when the ignition is on (key position "ON") and the engine is not running then. the mass air flow sensor or the electronic engine control unit may be faulty.
3. If the engine is idling (even if the output voltage of the mass air flow sensor is not correct), then the cause is usually one of the following faults:
- A) Air flow through the mass air flow sensor is not normal, the air duct is disconnected, or the air filter element is clogged.
- b) Incomplete combustion of the working mixture in the cylinder, malfunction of spark plugs, ignition coils, injectors and compression failure.
- V) Intake manifold defect (air leak).
4. Even if there are no signs of a malfunction of the mass air flow sensor, check that it is installed correctly (air flow direction).
Note:
- On a new car (mileage less than 500 km) The mass air flow sensor reading will be approximately 10% higher than the actual air flow.
- It is recommended to use an accurate digital voltmeter when carrying out checks.
- Before starting the test, it is necessary to warm up the engine so that the coolant temperature reaches 80-90°C.
Sensor test
1. Measure the voltage between the terminals "2" (signal) And "1" ("weight") connector on the sensor side under the specified conditions when the connector is connected.
- A) Check the voltage when the ignition key is set to "ON" (ON) and the engine is idling.
- Rated value: 0.5V
- b) Check the voltage when the engine is running at 2000 rpm.
- Rated value: 1.0V
2. If the measured tension differs from nominal value replace the gauge of the mass expense of air.