Nissan Maxima QX

since 1993 of release

Repair and car operation

Check of a condition and replacement of the sensor of measurement of weight of an air stream (MAF)

The MAF sensor is placed in an air inlet sleeve. As a sensitive element in the sensor the filament is used. A problem of the sensor is quantity measurement (on weight) air soaked up in the engine. Flowing round a sensor filament, the air stream causes its cooling. Change of temperature of a sensitive element is transformed to a peak electric signal and sent by the sensor on RSM. On the basis of the analysis of accepted information of RSM defines demanded duration of impulses of opening of injectors of injection. 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) - a principle of functioning and codes of malfunctions).

CHECK

PERFORMANCE ORDER

Performance described below procedure can lead to entering in memory of OBD of malfunction which will be highlighted by a control lamp “Check the engine”. On termination of check and the corresponding regenerative repair do not forget to clear memory of system (see. The section System of onboard diagnostics (OBD) - a principle of functioning and codes of malfunctions).

1. Before starting check actually the MAF sensor, make sure of serviceability of giving on it of a food and estimate quality of grounding.
2. Disconnect from the MAF sensor electroconducting. Also connect positive щуп the voltmeter to the plug white-black (1993 and 1994) / red (with 1995) wires of the contact socket. Negative щуп earth on weight. Include ignition (the engine do not start), - the measuring instrument should register the tension close to tension of the battery, 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 Head Onboard electric equipment).
3. On models 1993 and 1994 of вып. check serviceability of grounding of the plug of a black wire of a plait, - conductivity on weight should take place.

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

5. Start the engine on single turns and repeat measurement, - this time the device should register the indication of 1.0 ÷ 1.7 Century. With increase in frequency of rotation of the engine alarm tension also should increase (up to 3.0 In). Unfortunately, in the conditions of garage сымитировать operation of the engine under loading it is not obviously possible, however, the dependence of tension described above on turns should be traced absolutely accurately.
6. Positive results described above check confirm serviceability of the MAF sensor. Now it is necessary to check electroconducting of a chain of the sensor on 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 carrying out diagnostics and the corresponding regenerative repair of RSM.

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

REPLACEMENT

PERFORMANCE ORDER

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

1. Disconnect from the sensor electroconducting.

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

3. Establish the new sensor and connect to it electroconducting.