8.5. Check of a state and replacement of the sensor of measurement of mass of an air stream (MAF)

The MAF sensor is placed in an air inlet sleeve. As a sensitive element in the sensor filament is used. A problem of the sensor is measurement of quantity (on weight) the air which is soaked up in the engine. Flowing round sensor filament, the air stream causes its cooling. Change of temperature of a sensitive element is transformed to an amplitude electric signal and sent by the sensor to RSM. On the basis of the analysis of the accepted information of RSM determines the required duration of impulses of opening of injectors of injection. The failure of the MAF sensor leads to record in memory of system of self-diagnostics of the corresponding code of malfunction (see the Section System of Onboard Diagnostics (OBD) - the principle of functioning and codes of malfunctions).



 Implementation of the procedure described below can lead to entering in memory of OBD of malfunction which will be highlighted by a control lamp "Check the engine". Upon completion of check and the corresponding recovery repair do not forget to clear memory of system (see the Section System of Onboard Diagnostics (OBD) - the principle of functioning and codes of malfunctions).

1. Before starting check actually of the MAF sensor, make sure of serviceability of giving on it of food and estimate quality of grounding.
2. Disconnect an electrical wiring from the MAF sensor. Also connect the positive probe of the voltmeter to the plug of white-black (1993 and 1994) / red (since 1995) wires of the contact socket. Ground the negative probe on weight. Include ignition (the engine do not start), - the measuring instrument has to register tension close to battery tension, otherwise check a condition of the ECCS relay and a chain of the corresponding electric contour (see schemes of electric connections at the end of the Head Onboard electric equipment).
3. On models 1993 and 1994 of of the issue check serviceability of grounding of the plug of a black wire of a plait, - conductivity on weight has to take place.

4. Restore initial connection of an electrical wiring to the MAF sensor and probe the positive probe of the voltmeter the plug of a white wire from a reverse side of the contact socket (the negative probe of the voltmeter ground on weight) (for more details see the Head Onboard electric equipment). At the included ignition (the engine do not start) tension about 0.5 (1993 and 1994)/1.0 (since 1995) Century here has to take place.

5. Start the engine on single turns and repeat measurement, - this time the device has to register 1.0 ÷ 1.7 V. S testimony increase in frequency of rotation of the engine alarm tension also has to increase (up to 3.0 B). Unfortunately, in the conditions of a garage to simulate operation of the engine under loading the dependence of tension on turns described above absolutely accurately does not have to is obviously possible to be traced, however.
6. Positive results of the check described above confirm serviceability of the MAF sensor. Now it is necessary to check a sensor chain electrical wiring for existence of signs of breaks. If it is not possible to reveal any deviations, the car should be driven away on car repair shop for performing diagnostics and the corresponding recovery repair of RSM.

 Deeper diagnostics of the MAF sensor (some deviations cannot be revealed by means of the voltmeter) can be also made in the conditions of car repair shop.



 The MAF sensor placed in the plastic case is replaced complete with a metal sleeve of an air inlet in which it is fixed. You do not make attempts of extraction of the sensor from a sleeve.

1. Disconnect an electrical wiring from the sensor.

2. Release a collar of fastening of the sensor in a sleeve of an air inlet and turn out four fixing screws.

3. Install the new sensor and connect to it an electrical wiring.