Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Air Flow Meter

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OPERATION



See Figure 1



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Fig. Fig. 1: Air flow meter assembly

Only the 1984 E15ET engine uses an air flow meter sensor. All other fuel injected engines use a mass air flow type sensor. The air flow meter measures the amount of air entering the intake manifold and sends a voltage signal to the control unit. As air enters the intake, the incoming air moves the sensor flap. A potentiometer is connected to the sensor flap. allowing sensor flap movement to be converted into a voltage signal. Since air flow is directly proportional to engine load, this signal is the principal input for determining fuel injection duration.

TESTING



  1. Disconnect the air flow sensor electrical connector.
  2.  
  3. Connect an ohmmeter between terminals 33 and 26 . Then between terminals 33 and 26 . The measurement obtained in both tests should be 280-400 ohms.

    If the both measurements were within specifications, proceed to the next step.
     
    If either measurement was not within specifications, replace the VAF sensor and retest.
     

  4.  
  5. Connect the ohmmeter between terminal 33 and 31 of the air flow sensor. Operate the flap manually. The door should move smoothly, without binding or sticking. The resistance must increase and decrease smoothly and without any wide fluctuations. Open and close the vane slowly several times while observing the ohmmeter closely.

    If there are any major fluctuations in the readings or the readings indicates an open or a short, replace the air flow meter and retest.
     
    If the air flow meter operates correctly, examine the connector and wiring harness for corrosion or damage.
     

  6.  

 
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