Mass Airflow
Mass airflow is determined by processing the MAF sensor signal through a preprogrammed comparative data table in the ECM. A typical MAF sensor consists of a screen to break up airflow, an air temperature sensing resistor, a heated film and electronic module mounted on the sensor.
Airflow is directed over the heated film. The cooling effect of air flowing over the heated film in the sensor changes its resistance. Additional electrical power is then required to maintain the sensor at 165°F (75°C) above the incoming air temperature. This current is measured and converted to a digital signal (30-150 Hz), which is then sent to the ECM. The ECM uses the signal to calculate air intake in grams per second. The ECM compares this signal with those stored in memory.
Using calculations of mass airflow, engine temperature and RPM, the ECM calculates the exact amount of fuel required to provide a proper air/fuel ratio (14.7:1). The MAF sensor readings and fuel requirement calculations are made by the computer every 6-14 milli-seconds (approximately 160 calculations per second). See Fig 1 .