Hyundai Coupes/Sedans 1994-1998 Repair Guide

Airflow Sensor

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OPERATION



Two types of airflow sensors are used on these vehicles. Early model vehicles use a Vane Air Flow (VAF) sensor, while late model vehicles use a Mass Air Flow (MAF) Sensor. The air flow sensors measure the intake air volume. The ECM uses this signal to calculate basic fuel injection timing. The air flow sensors are located in the intake tract between the air filter and the throttle body.

TESTING



See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Vane air flow sensor schematic-early model engines

Vane Air Flow (VAF) Sensor

VAF sensors can be identified by the presence of a six terminal square connector.

This test requires the use of a multimeter capable of measuring frequency.

  1. Start the engine and allow it to reach operating temperature.
  2.  
  3. Backprobe the sensor electrical harness between terminal 3 and 6.
  4.  
  5. Frequency should be 27-33 Hz at idle and raise steadily to 60-80 Hz as rpm is increased to 2000rpm.
  6.  
  7. If frequency is not within specification, check the sensor power and ground circuit.
  8.  
  9. If power and ground circuits are functional, sensor is faulty.
  10.  

Mass Air Flow (MAF) Sensor

See Figures 2 and 3



Click image to see an enlarged view

Fig. Fig. 2: Mass air flow sensor schematic-late model engines except 1.5L (VIN E) Turbo



Click image to see an enlarged view

Fig. Fig. 3: Mass air flow sensor schematic-1.5L (VIN E) Turbo

MAF sensors can be identified by the presence of either a four terminal or six terminal flat connector.

  1. Start the engine and allow it to reach operating temperature.
  2.  
  3. On all engines except 1.5L (VIN E), backprobe the sensor electrical harness between terminal 1 and ground.
    1. Voltage should be 0.7-1.1 volts at idle and raise steadily to 1.3-2.0 as rpm is increased to 3000rpm.
    2.  

  4.  
  5. On 1.5L (VIN E) normally aspirated engines, backprobe the sensor electrical harness between terminal 4 and ground.
    1. Voltage should be 0.94-0.98 volts at idle and raise steadily to 1.76-1.79 as rpm is increased to 3000rpm.
    2.  

  6.  
  7. On 1.5L (VIN E) turbocharged engines, backprobe the sensor electrical harness between terminal 3 and ground.
    1. Voltage should be 2.0-2.6 volts at idle and raise steadily to 2.6-3.3 as rpm is increased to 3000rpm.
    2.  

  8.  
  9. If voltage is not within specification, check the sensor power and ground circuit.
  10.  
  11. If power and ground circuits are functional, sensor is faulty.
  12.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Label and disconnect the sensor electrical harness
  4.  
  5. Loosen the hose clamps attaching the sensor to the intake duct.
  6.  
  7. Carefully remove the sensor.
  8.  

To Install:
  1. Carefully install the sensor and tighten the hose clamps securely
  2.  
  3. Connect the sensor electrical harness
  4.  
  5. Connect the negative battery cable.
  6.  

 
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