Toyota Pick-ups, Land Cruiser, and 4 Runner 1997-00

Mass Air Flow (MAF) Meter

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OPERATION



A Mass Air Flow (MAF) meter is used on all engines. This meter measures the amount of air flowing through the intake system. It is used by the ECM to calculate air/fuel mixture.

The MAF meter, or sensor, has a platinum hot wire, a thermistor and a control circuit, all in a plastic housing. The hot wire and thermistor are located in the intake air bypass of the housing, detecting any changes in the intake air temperature. The hot wire is maintained at the set temperature by controlling the current flow through the hot wire. This current flow is measured as the output voltage of the MAF meter.

A failed MAF meter should set a Diagnostic Trouble Code (DTC).

TESTING



  1. Remove the air intake hose.
  2.  
  3. Turn the ignition switch to the ON position.
  4.  
  5. Using a voltmeter, attach the positive terminal probe to the terminal VG , and the negative probe to terminal E3 .
  6.  



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Fig. Testing the Mass Air Flow (MAF) meter E3 and VG circuits1FZ-FE and 5VZ-FE engines



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Fig. Testing the Mass Air Flow (MAF) meter E3 and VG circuits2RZ-FE and 3RZ-FE engines



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Fig. Testing the Mass Air Flow (MAF) meter E2G and VG circuits2UZ-FE engine

  1. Blow air into the MAF meter, then check that the voltage fluctuates.
  2.  
  3. Turn the ignition switch to the OFF position.
  4.  
  5. Install the air intake hose.
  6.  

REMOVAL & INSTALLATION



2RZ-FE and 3RZ-FE Engines
  1. Disconnect the MAF harness and the IAT harness along with the wire clamps.
  2.  
  3. Loosen the air cleaner hose clamp.
  4.  
  5. On the 3RZ-FE, disconnect the air hose from the air cleaner cap.
  6.  
  7. Loosen the four clips, and then remove the air cleaner cap with the meter attached.
  8.  
  9. Remove the four nuts, and then the MAF meter and gasket from the cap.
  10.  



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Fig. Exploded view of the MAF meter arrangement2RZ-FE and 3RZ-FE engines

  1. Discard the gasket.
  2.  

To install:

  1. Place a new gasket on the air cleaner cap.
  2.  
  3. Install the MAF meter and tighten the nuts to 74 inch lbs. (8 Nm).
  4.  
  5. Install the meter and cap assembly on the air cleaner housing.
  6.  

5VZ-FE Engine
  1. Disconnect the air cleaner cap from the MAF meter.
  2.  
  3. Detach the harness from the meter.
  4.  
  5. Remove the mounting bolts for the meter. Lift off the meter and discard the gasket.
  6.  



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Fig. Detach the electrical connector from the Mass Air Flow (MAF) meter



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Fig. Remove the bolts securing the meter5VZ-FE engine



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Fig. The Mass Air Flow (MAF) meter must be installed in the correct direction



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Fig. Loosen the clamp from the air intake hose and then remove the Mass Air Flow (MAF) meter



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Fig. Inside the Mass Air Flow (MAF) meter there is a very fragile piece of wire. NEVER poke a tool down into the air flow meter for damage to the unit will occur

To install:

  1. Place a new gasket in position, then tighten the meter to the cap assembly to 61 inch lbs. (7 Nm).
  2.  
  3. Connect the harness to the meter.
  4.  
  5. Attach the meter and cap assembly to the air cleaner housing.
  6.  

2UZ-FE Engine


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Fig. Remove the two screws securing the meter2UZ-FE Engine

  1. Disconnect the MAF meter connector.
  2.  
  3. Remove the two retainer screws.
  4.  
  5. Lift off the MAF meter.
  6.  
  7. Installation is the reverse of removal. Verify the electrical connector is secure.
  8.  

1FZ-FE Engine
  1. Disconnect the MAF meter harness and wire clamps.
  2.  
  3. Separate the cruise control actuator cable from the unit.
  4.  
  5. Loosen the air cleaner hose.
  6.  
  7. Disconnect the three clips, then remove the wing nut, air cleaner cap and meter assembly.
  8.  
  9. Unbolt the meter from the cap. Discard the gasket.
  10.  

To install:

  1. Secure the MAF meter to the cap with a new gasket.
  2.  
  3. Install the cap/meter assembly to the air cleaner housing.
  4.  
  5. Attach the air cleaner hose to the unit.
  6.  
  7. Attach the cruise control actuator cable.
  8.  
  9. Connect the MAF meter harness and wire clamps.
  10.  

 
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