F 350 4WD Super Duty V8-6.4L DSL Turbo (2008)
Air Flow Meter/Sensor: Description and Operation
MASS AIR FLOW (MAF) SENSOR
Mass Air Flow (MAF) Sensor
The MAF sensor provides a signal to the PCM proportional to the intake air mass. The MAF sensor uses a hot wire sensing element to measure the
amount of air entering the engine. The hot wire is maintained at a constant temperature above ambient. Air passing over the hot wire cools the wire. The
current required to maintain the temperature of the hot wire is proportional to the air flow.
The MAF sensor is a digital sensor that provides an output signal of varying frequency. The signal's time period is proportional to the flow rate crossing
the sensor. The greater the air flow the greater the time period. The time period varies from 130 microseconds (15 kHz) at a low flow or idle condition,
to 530 microseconds (1.9 kHz) at a high flow rate condition. If the sensor element is broken the diagnostic mode default output of the sensor will be
4650 microseconds (215 Hz).
