Nissan Maxima 1993-1998 Repair Guide

Mass Air Flow Sensor

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OPERATION



The Mass Air Flow (MAF) sensor directly measures the amount of air flowing into the engine. The sensor is mounted between the air cleaner assembly and the air cleaner outlet tube.

The sensor utilizes a hot wire sensing element to measure the amount of air entering the engine. The sensor does this by sending a signal, generated by the sensor when the incoming air cools the hot wire, to the ECM. The signal is used by the ECM to calculate the injector pulse width, which controls the air/fuel ratio in the engine.

TESTING



See Figures 1, 2, 3 and 4



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Fig. Fig. 1: Backprobe the connector at terminal B as shown (1993-94)



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Fig. Fig. 2: On 1995-98 vehicles, backprobe terminal 1 for testing

  1. Using a multimeter, check for voltage by backprobing the MAF sensor connector, as illustrated.
  2.  



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Fig. Fig. 3: To backprobe the connector, remove the rubber boot from the back of the connector

  1. With the ignition switch ON and the engine stopped, voltage should be less than 1.0 volt.
  2.  



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Fig. Fig. 4: The voltage should be less than 1 volt with the key in the ON position

  1. With the engine idling at operating temperature, voltage should be 1.0-1.7 volts.
  2.  
  3. With the engine running at approximately 2,500 rpm, voltage should be 1.5-2.1volts.
  4.  

It is important to watch for a linear voltage rise in response to increases in engine rpm, up to about 4000 rpm.

  1. If voltage is not within specifications, check the power and ground circuits.
  2.  
  3. If the power and ground circuits test okay, the MAF sensor may be faulty.
  4.  

REMOVAL & INSTALLATION



See Figure 5

  1. Loosen the hose clamps securing the air tube.
  2.  
  3. Disconnect the air tube from the MAF sensor and throttle body.
  4.  
  5. Disconnect the MAF sensor electrical harness.
  6.  



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Fig. Fig. 5: Use a small pick to push the metal clip open while gently pulling back on the connector

  1. Remove the MAF sensor attaching bolts.
  2.  
  3. Carefully remove the MAF sensor from the air box.
  4.  

To install:
  1. Position the MAF sensor in the air box.
  2.  
  3. Install the MAF sensor attaching bolts and tighten to 13-16 ft. lbs. (18-22 Nm).
  4.  
  5. Connect the MAF sensor's electrical harness.
  6.  
  7. Connect the air tube to the MAF sensor and throttle body.
  8.  
  9. Tighten the hose clamps securing the air tube.
  10.  

 
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