Suzuki Samurai/Sidekick/Tracker 1986-1998 Repair Guide

Mass Airflow (MAF) Sensor

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OPERATION



See Figures 1, 2 and 3

Only the 1.6L MFI and 1.8L engines use Mass Airflow (MAF) sensors.

The Mass Airflow (MAF) sensor consists of a heat resistor, a metering duct, a straightening net and a control circuit.



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Fig. Fig. 1: Mass Airflow (MAF) sensor circuit-1996-98 1.8L engines



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Fig. Fig. 2: The MAF sensor used on 1.6L engines is mounted between the air intake tube and the air cleaner housing



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Fig. Fig. 3: The MAF sensor is an integral part of the throttle body on 1.8L engines

The MAF sensor detects the amount of airflow through the throttle body, and sends a reference signal to the ECM. The ECM utilizes this information to help manage the engine.

The MAF sensor is a thermal control type and includes a heat resistor and a control circuit. The heat resistor is cooled by the incoming air stream entering the throttle body opening. The control circuit manages the electrical current necessary to keep the heat resistor temperature within a factory-set range. The ECM reads the amount of voltage in the current necessary to keep the heat resistor warm, and can calculate the amount of air entering the engine. The ECM uses this information to provide the proper amount fuel to the engine under varying load conditions.

On 1.6L MFI engines, the MAF sensor is mounted between the air cleaner housing and the air intake tube (leading to the throttle body). On 1.8L engines, the MAF sensor is an integral part of the throttle body and cannot be separately replaced.

TESTING



1.6L MFI Engine

See Figure 4

It is necessary to use a Digital Volt-Ohmmeter (DVOM) set to the voltmeter function, or a high-impedance (10 kilohms/volts minimum) voltmeter, otherwise erroneous readings may occur.

  1. Use the DVOM to measure the battery voltage (positive DVOM lead to the positive battery terminal, and the negative DVOM lead to the negative battery terminal). Note the battery voltage.
  2.  
  3. Remove and position the ECM along with its bracket, relays, fuse panel and wiring harness on the floor of the vehicle. Position clean paper or mat on the floor first so that no hair, dirt or dust can enter the ECM accidentally. Reattach the wiring harness connectors to the ECM. This is done to allow access to the unit during testing.
  4.  
  5. Disengage the wiring harness connector from the MAF sensor.
  6.  
  7. Attach the positive lead of the DVOM to the B+ terminal (positive battery voltage) of the MAF sensor wiring harness connector. Connect the negative DVOM lead to a good engine ground.
  8.  



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Fig. Fig. 4: Disengage the wiring harness connector from the MAF sensor, then attach a DVOM (set to the voltmeter function) to the B+ terminal of the sensor connector and a good ground

  1. Turn the ignition switch ON and ensure that the voltage at the connector is the same as the battery voltage noted earlier. If the voltage is not the same, inspect the wiring harness for an open or short circuit.
  2.  
  3. Turn the ignition switch OFF , then reattach the wiring harness connector to the MAF sensor connector.
  4.  
  5. Backprobe one of the DVOM leads to ECM terminal E32-9, and the other DVOM lead to a good chassis ground. Turn the ignition switch ON and read the voltage of terminal E32-9. The voltage observed should be 1.0-1.6 volts.
  6.  
  7. Start the engine and once again check the voltage at terminal E32-9. The voltage should be lower than 5 volts (exact specification is 1.7-2.0 volts) at idle and gradually rise as you increase engine speed (rpm).
  8.  
  9. If the voltage did not react as described, there is a problem in the wiring harness, the connectors, the MAF sensor or the ECM.
  10.  

1.8L Engine

To test the MAF sensor, a diagnostic scan tool is necessary.

  1. Attach a scan tool to the Data Link Connector (DLC) with the ignition switch OFF .
  2.  
  3. Start the engine and allow it to reach normal operating temperature.
  4.  
  5. Using the scan tool, check the values displayed for "MASS AIR FLOW RATE." The airflow rate should be 0.20-0.53 lb. per minute (1.5-4.0 grams per second) at idle, and 0.66-1.32 lbs. per minute (5.0-10.0 grams per second) at 2,500 rpm.
    1. If the values displayed by the scan tool do not match those specified, the MAF sensor is faulty; replace the throttle body with a new one.
    2.  
    3. If the values displayed by your scan tool match those specified, the problem is an intermittent fault in the circuit or a faulty ECM.
    4.  

  6.  

REMOVAL & INSTALLATION



1.6L MFI Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Disengage the wiring harness connector from the MAF sensor.
  4.  
  5. Remove the air cleaner upper housing retainers, then lift the housing and MAF sensor up and out of the engine compartment.
  6.  
  7. Separate the MAF sensor from the upper air cleaner housing.
  8.  


WARNING
To avoid accidental MAF sensor damage, do not attempt to disassemble the MAF sensor. Also, do not expose the MAF sensor to electrical shocks, and do not insert fingers or any other object into the MAF sensor hole. Do not touch the air-straightening net.

To install:
  1. Inspect the MAF sensor seal for deterioration or damage.
  2.  
  3. Install the MAF sensor in the air cleaner upper housing, ensuring that the seal is properly engaged.
  4.  
  5. Install the upper housing and MAF sensor onto the lower air cleaner housing, then tighten the retainers securely.
  6.  
  7. Reattach the wiring harness connector to the MAF sensor.
  8.  
  9. Conenct the negative battery cable.
  10.  
  11. Start the engine and ensure MAF sensor operation.
  12.  

1.8L Engine

The MAF sensor is an integral part of the throttle body and cannot be separated from it. For throttle body removal and installation procedures, refer to Fuel System .

 
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