See Figure 1
The air flow sensor, mounted on the outside of the air cleaner assembly, uses a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes the wire to cool, which in turn creates an analog signal which is relayed to the electronic control unit where a intake mass air calculation is made. The electronic control module uses this information to determine the required fuel injector pulse width in order to provided the optimum air/fuel ratio.
The airflow sensor electronics module and body are calibrated as a unit and must be tested as a complete assembly.
- With the key OFF , check and make sure all engine control components are installed.
- Unfasten the airflow sensor harness and connect a breakout box to the sensor. Connect the wire harness to the breakout box.
- With the wheels blocked, start the vehicle and place in PARK or NEUTRAL . Allow the vehicle to reach normal operating temperature.
- Using a multimeter, measure the voltage between test pin 14 at the breakout box, and the positive terminal of the battery or starter solenoid.
- If the sensor is working correctly, at idle, the voltage reading should be 0.6-0.7 volts.
- If the reading is below 0.6, perform the same test while applying throttle. If the voltage is below 0.8 volts while at throttle, replace the airflow sensor.
REMOVAL & INSTALLATION
When the battery cable has been disconnected and reconnected, some abnormal drive symptoms may occur while the powertrain control module relearns its adaptive strategy. The vehicle may need to be driven 10 miles (16 km) or more to relearn the adaptive strategy.
- Disconnect the negative battery cable.
- Unfasten the wire harness attached to the airflow sensor.
- Loosen the air cleaner outlet tube clamp at the airflow sensor. Remove the outlet tube from the airflow sensor.
- Remove the four retainer screws securing the airflow sensor to the air cleaner housing.
- Remove the airflow sensor from the air cleaner. Remove and discard the gasket between the air cleaner and airflow sensor.
- Remove all gasket from both mating surfaces.
- Position the airflow sensor and new gasket to the air cleaner and secure in place with the retainer screws. Tighten the retainer screws to 88 inch lbs. (10 Nm).
- Install the inlet tube to the airflow sensor and tighten the clamp to 18-27 inch lbs. (2-3 Nm).
- Fasten the wire harness to the airflow sensor.
- Connect the negative battery cable.
- Road test the vehicle.