Mass Air Flow (MAF) Sensor Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide
OPERATION See Figures 1, 2 and 3
Fig. 1: Mass air flow sensor with throttle body fuel injection
Fig. 2: Operation of a film type air flow sensor with throttle body fuel injection
Fig. 3: Mass air flow sensor with multi-point fuel injection
All Sentra/Pulsar fuel injected engines, except the E15ET engine use a MAF sensor input to calculate engine load. The sensor is mounted either in the air cleaner housing on MFI engines or in the throttle body housing on TBI engines. The MAF uses a heated wire or film which is stretched across the incoming air flow. The element requires more electrical current to maintain its temperature, as the amount of intake air flow increases. i ncreases. By measuring the amount of current necessary to maintain the temperature of the wire or film, the control unit can calculate the volume of air entering the engine. Since the volume of air entering the engine is directly proportional to the amount of engine load, the ECM can determine the operating load of the engine, by monitoring the MAF signal wire.
TESTING E16i Engine METHOD A See Figure 4
Fig. 4: ECM connector terminal identification-E16i engine
1. 2. 3.
Pull back the mass air flow sensor harness harness protective cover, cover, exposing the wire terminal ends. Turn the ignition ON . Connect a voltmeter between between MAF sensor connector E and and a known good engine. Battery voltage should exist. If battery voltage does does not not exist, check check the MAF sensor power supply circuitry. If battery voltage does exist, proceed to the next step. Connect a voltmeter between ECM connector 31 and 31 and a known good engine ground. Start the engine and and allow it to fully warm up before continuing. The voltage reading should change change by racing the engine with the accelerator accelerator pedal, from 0 to approximately 5.0 volts. If the voltage is not as specified, check the wiring between the MAF sensor and the ECM. If the wiring is okay, replace the MAF sensor. • •
4. 5. 6.
METHOD B See Figure 5
Fig. 5: Testing the mass air flow sensor, with the sensor removed-E16i engine
1. 2. 3.
Remove the MAF sensor from the vehicle. Connect positive (+) battery battery voltage to sensor sensor terminal E . Connect terminal C to to battery ground (-). Connect a voltmeter between sensor terminals A terminals A and and D. The meter should read 1.5-2.0 volts. If battery voltage was within specifications, specifications, proceed to the next next step. If battery voltage was not within within specifications, replace the MAF sensor. • •
4.
With the meter and battery connected as in the previous step, blow blow across the sensor film. The meter should read between 2.5-4.0 volts. If the reading is not within specifications, replace the MAF sensor.
CA16DE Engine See Figure 6
Fig 6: ECM connector terminal identification-CA16DE engine
1. 2. 3. 4.
Visually inspect the MAF sensor hot wire for dirt, dust, or damage. Clean Clean or replace if necessary. Pull back the mass air flow sensor harness harness protective cover, cover, exposing the wire terminal ends. Turn the ignition ON . Connect a voltmeter between between MAF sensor connector B and a known good engine. Battery voltage should exist. If battery voltage does does not not exist, check check MAF sensor power power supply circuitry. If battery voltage does exist, proceed to the next step. Connect a voltmeter between ECM connector 31 and 31 and a known good engine ground. Start the engine and and allow it to fully warm up before continuing. The voltage reading should be be approximately 1.5 volts at idle. If the voltage is not as specified, check the wiring between the MAF sensor and the ECM. If the wiring is okay, replace the MAF sensor. • •
5. 6. 7.
GA16i and CA18DE Engines See Figures 7, 8 and 9
Fig. 7: Mass air flow sensor connector terminal identification-GA16i engine
Fig. 8: Mass air flow sensor connector terminal identification-CA18DE engine
Fig. 9: ECM connector terminal identification-GA16i and CA18DE engines
1. 2. 3. 4.
Visually inspect the MAF sensor hot wire for dirt, dust, or damage. Clean Clean or replace if necessary. Pull back the mass air flow sensor harness harness protective cover, cover, exposing the wire terminal ends. Turn the ignition ON . Connect a voltmeter between the MAF sensor connector connector B and a known good engine. Battery voltage should exist. If battery voltage does does not not exist, check check MAF sensor power power supply circuitry. If battery voltage does exist, proceed to the next step. Connect a voltmeter between ECM connector 15 and and a known good engine ground. Start the engine. Allow the engine to fully warm up before continuing. The voltage reading at idle should be approximately 1.0 1.0 volt for the GA16i engine, engine, or 1.5 volts for the GA18DE engine. If the voltage is out of range, before replacing the sensor, check the wiring between the MAF sensor and the ECM. • •
5. 6. 7.
1.6L (GA16DE) and 2.0L (SR20DE) Engines See Figures 10, 11, 12, 13, 14, 15, 16 and 17
Fig. 10: Mass air flow sensor connector terminal identification-1991-94 GA16DE engine
Fig. 11: Mass air flow sensor connector terminal identification-1991-94 SR20DE engine
Fig. 12: Inspect the heated wire for damage, dust or dirt build-up-1991-94 GA16DE engine
Fig. 13: Mass air flow sensor connector terminal identification-1995-96 GA16DE and SR20DE engines
Fig. 14: Mass air flow sensor parameter chart-1991-94 GA16DE engine
Fig. 15: Mass air flow sensor parameter chart-1991-94 SR20DE engine
Fig. 16: Mass air flow sensor parameter chart-1995-96 GA16DE engine
Fig. 17: Mass air flow sensor parameter chart-1995-96 SR20DE engine
1. 2. 3. 4.
5. 6.
Pull back the mass air flow sensor harness harness protective cover, cover, exposing the wire terminal ends. Turn the ignition ON and and start the engine. Allow the engine to fully warm up before continuing. Turn the ignition OFF . Connect a voltmeter between between MAF sensor connector A connector A and and a known good engine ground on 1991-94 vehicles. For testing of 1995-95 vehicles, make connection between MAF terminal 1 and a known good engine ground. Turn the ignition ON , but do not start the engine. The voltage reading should be less than 1.0 volt. Start the engine and and observe the voltmeter. Compare the readings to the specifications give on the MAF sensor parameter chart.
If the voltages are out of range, perform the following checks before replacing the MAF sensor:
7. Visually inspect the MAF sensor hot wire for dirt, dust, or damage. Clean if necessary. If okay, check wiring and power supply circuitry.
REMOVAL & INSTALLATION See Figures 18 and 19
Fig. 18: With the upper air cleaner housing cover off, unfasten the MAF sensor outer mounting bolts
Fig. 19: Some sensors may also be fastened from inside the air cleaner housing
