Subaru Coupes/Sedans/Wagons 1985-1996 Repair Guide

Airflow Meter

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REMOVAL & INSTALLATION



See Figure 1

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Fig. Fig. 1: Airflow meter assembly-1.8L engine

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air intake boot by loosening the clamps and sliding the boot from the airflow meter.
  4.  
  5. Disconnect the airflow meter electrical harness.
  6.  
  7. Remove the airflow meter attaching bolts.
  8.  
  9. Remove the airflow meter and discard the gasket.
  10.  
  11. Clean all gasket material from both mating surfaces.
  12.  

To install:
  1. Using a new gasket, install the airflow meter. Tighten the bolts snugly, but be careful as the air cleaner housing is plastic and could break easily.
  2.  
  3. Install the airflow meter electrical harness.
  4.  
  5. Install the intake air boot and tighten the clamps securely.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Start the engine and listen for air leaks around the intake boot and airflow meter.
  10.  

TESTING



See Figures 2, 3, 4 and 5

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Fig. Fig. 2: Airflow meter testing-1.8L engine



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Fig. Fig. 3: Testing the resistance between terminal B and ground



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Fig. Fig. 4: Checking terminal R voltage



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Fig. Fig. 5: Measuring the voltage between terminals W and B

  1. Check for leaks or damage in the connection between the air intake boot and the airflow meter. Repair if necessary.
  2.  
  3. Disconnect the electrical connector from the airflow meter, then remove the air intake boot, and the airflow meter from the air cleaner assembly.
  4.  
  5. Check the exterior of the airflow meter for damage.
  6.  
  7. Check the interior of the airflow meter for foreign particles, water, or oil in the passages, especially in the bypass. If any of the above faults are noted, replace the airflow meter.
  8.  
  9. If none of the above faults are noted, proceed as follows:
    1. Turn the ignition switch to the OFF position, then install the airflow meter onto air cleaner assembly.
    2.  
    3. Disconnect the airflow meter electrical connector, then slide back the rubber boot.
    4.  

  10.  

Conduct the following test by connecting the tester pins to the connector terminals on the side from which the rubber boot was removed.

    1. Using an ohmmeter, measure the resistance between terminal B on the connector and ground. The ohmmeter should read 10 ohms. If the ohmmeter reading exceeds 10 ohms, check the harness and internal circuits of the control unit for discontinuity.
    2.  
    3. Turn the ignition switch to the ON position.
    4.  
    5. Using a voltmeter, measure voltage across power terminal R and ground. The voltmeter should read 10 volts. If specifications are not as specified, check the power line (battery, fuse, control unit, harness connector, etc).
    6.  
    7. Connect the airflow meter electrical connector. Using a voltmeter, connect the positive lead of the tester to terminal W and the negative lead of the tester to terminal B, and measure voltage across the 2 terminals. The voltmeter should read 0.1-0.5 volts. If the readings are not as specified, replace the airflow meter.
    8.  
    9. Remove the upper section of the air cleaner assembly, then blow air in from the air cleaner side and check if voltage across terminals W and B is higher than the reading obtained in Step f. If not, replace the airflow meter.
    10.  


 
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