Air Flow Meter/Sensor: Description and Operation
ENGINE CONTROL COMPONENTSMass Air Flow (MAF) Sensor
The MAF sensor provides a signal to the powertrain control module (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 signals time period is proportional to the flow rate crossing the sensor. The greater the air flow the shorter the time period. The time period varies from 1480 microseconds at a low flow or idle condition, to 106 microseconds at a high flow rate condition.
The MAF sensor is integrated with the intake air temperature (IAT) sensor, known as the MAF/IAT sensor.
The MAF/IAT sensor is located in the intake air tube between the air filter housing and the turbocharger intake.
