The mass air flow sensor is a thermopneumatic type IVKSH 407282000, installed in the intake system after the air filter.
The sensor detects the amount of air entering the cylinders while the engine is running.
There is a platinum filament in the sensor housing. During operation, it heats up to a temperature of 150 ° C.
The air flow passing through the sensor housing removes more heat from it, the higher the air flow rate.
The electronic unit calculates the mass flow rate of the incoming air by the amount of electric power that is spent to maintain the specified temperature of the thread.
Since the temperature of the air itself affects the cooling of the thread, a thermistor is installed in the sensor housing, which changes its resistance in accordance with the temperature of the air flow entering the system.
Based on its readings, the electronic unit makes adjustments to the operation of the electrical circuit for heating the thread, thereby compensating for temperature fluctuations caused by changes in weather conditions.
The control system informs the driver about the occurrence of a malfunction in the mass air flow sensor circuit by turning on the KMSUD signaling lamp, the fault codes are stored in the memory of the electronic unit, and the engine will be switched to standby mode.
- 1. Disconnect the wire from the "negative" terminal of the battery.
- 2. Disconnect connector 1 from mass air flow sensor 3. Loosen the clamps, disconnect the air supply hoses 2 and remove the sensor 3.
3. Install the new sensor in reverse order.
Checking the mass flow sensor.
- 1. Remove the mass air flow sensor.
- 2. Connect a voltmeter to pins "2" and "3" of the sensor connector.
Supply 12 V DC to pins 1 and 5 (“+” to pin “5”, and “–” to “1”). In this case, the voltmeter should show a voltage of 1.3–1.4 V.
Then briefly close contacts "4" and "5" between each other. At the same time, the voltmeter should show a voltage of about 8 V, and the platinum thread should become red-hot.
If at least one of these conditions is not met, replace the sensor.
Let's take a closer look at removing and checking the DMRV
Mass air flow sensor test circuit
Turn off the ignition and remove the negative terminal from the battery.
Prying off the spring clip of the block with an awl, disconnect the sensor connector.
We loosen the clamp screws with a screwdriver, remove the clamps and remove the mass air flow sensor from the air ducts.
Checking the MAF
On the pins of the electrical connector we put on short segments of a thin PVC tube, inserting the ends of the wires bare by 7–8 mm into them, we assemble the circuit shown in the figure.
When connecting the wires to the sensor, you need to be guided by the profile of the end of the connector.
We connect the wires to the battery last, making sure that the circuit is assembled correctly.
We take the readings of the voltmeter from the switch instrument switch.
For a good sensor, the voltage at pins 2 and 3 should be 1.3-1.4 V.
Turn on the switch for a short time and take the readings of the voltmeter.
For a healthy sensor, the voltage at pins 2 and 3 should increase to about 8 V.
The platinum thread is heated red-hot.
A defective sensor must be replaced.
Install the mass air flow sensor in reverse order.