The mass airflow meter or sensor, measures the amount of air which passes through it. The ECU uses this information to determine the operating condition of the engine, to control fuel delivery. A large quantity of air indicates acceleration, while a small quantity indicates deceleration or idle. Mazda used two types of meters in their vehicles.
One style uses a mechanical door or cone system connected to a variable resistor. The door/cone is pushed open by the incoming air, which in turn changes the resistance. The wider the door/cone is open, the larger the amount of air flow. This style is generally called a Mass Air Flow (MAF) meter.
The second style functions on a hot wire principle. A wire is heated to a certain temperature. The amount of voltage necessary to keep the wire at that temperature with air flowing over it is used to calculate airflow. The more air that flows over the wire, the cooler it will become and the more voltage will be required to heat it. This style is generally called a Mass Airflow Sensor (MAS).