Mass Airflow (MAF) Sensor

1999 Mercury Tracer LS, 4D Sedan, StandardSECTION Mass Airflow (MAF) Sensor
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2011 Mercury Milan, 2011 Mercury Mariner, 2011 Mercury Grand Marquis, 2011 Lincoln Town Car, and 2011 Lincoln Navigator L. However, it is still accessible from the selected car via links, so may be relevant.

The MAF sensor uses a hot wire sensing element to measure the amount of air entering the engine. Air passing over the hot wire causes it to cool. This hot wire is maintained at 200Β°C (392Β°F) above the ambient temperature as measured by a constant cold wire. The current required to maintain the temperature of the hot wire is proportional to the mass airflow. The MAF sensor then outputs a signal to the PCM proportional to the intake air mass. The PCM calculates the required fuel injector pulse width in order to provide the desired air/fuel ratio. This input is also used in determining transmission electronic pressure control (EPC), shift, and torque converter clutch (TCC) scheduling.

The MAF sensor is located between the air cleaner and the throttle body or inside the air cleaner assembly. Most MAF sensors have integrated bypass technology with an integrated IAT sensor. The hot wire electronic sensing element is replaced as an assembly. Replacing only the element may change the airflow calibration.

Fig 1: Throttle Body Contacting MAF Sensor Hot And Cold Wire Airflow Diagram
G06053891Courtesy of FORD MOTOR CO.
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