Mass Air Flow Sensor
Mass air flow sensor is installed to the intake air path upstream of throttle and measures air flow rate.
This mass air flow sensor is a backflow-detecting film and silicon element type sensor that can detects air flow rate of both direct flow and backflow. This mass air flow sensor outputs an air flow rate by using frequency signals.
The element part of this mass air flow sensor consists of a heater and temperature sensors installed to both top and bottom of the heater, one to each position. When air flows, the heat distribution around the heater changes and this produces a temperature difference between upstream and downstream. This temperature difference is detected as air flow rate.