An air flow, air mass or air mass flow sensor measures the amount of fresh air taken into the engine. A combustion engine needs air for the burning processes in the combustion chamber. The air flow sensor ensures the correct amount of fuel is delivered to the injectors.
An air mass sensor has various purposes. Where the air-intake is concerned, it measures the temperature of the fresh air. These measurements are constantly send to a calculator. The latter then calculates the amount of exhaust gasses will be produced by the burning processes in the engine.
To reduce the exhaust of gasses into the atmosphere when accelerating or slowing down, the calculator corrects the amount of fuel injected into the combustion chamber.
What does an air flow sensor look like?
An air flow sensor looks like a tube with a grid at either end. Two types of air flow sensors exist for cars. Air flow sensors are either vane meters or hot wire meters. The former has a spring-loaded air flap attached to a variable resistor. A hot wire sensor or maf sensor on the other hand works with an electric wire which is heated like a toaster wire. When cold air flows past the wire, its resistance decreases. The sonde transfers this information to the calculator.