MX-6 L4-1991cc 2.0L DOHC (1993)
Mass Air Flow Sensor: Description and Operation
^ A hot wire type mass air flow sensor measures the volume of air entering the intake system. Unlike a flap type sensor, which only measures air flow
volume, a mass air flow sensor measures the actual mass per unit time of air entering the engine. This is a more accurate measurement because any
given volume contains different quantities of air depending on air density.
^ The sensor converts the amount of air taken into the engine into an electric signal by using the heat transfer phenomenon between incoming air and a
heated resistor (wire). The ECU uses this information, together with input data from other sensors, to calculate fuel injector pulse ("ON" time) and
thus regulate air/fuel ratio.
^ A wire filament located in the intake air flow is heated by electric current. Intake air flow cools the wire, causing a decrease in resistance. As this
occurs, more current is required to maintain the ECU programmed reference temperature. At idle, very little air passes over the wire and the cooling
effect is small. Resistance through the wire is high and very little additional current is required to maintain its temperature. As the throttle is opened
and air flow over the hot wire increases, the cooling effect also increases, requiring more current to maintain its temperature. The ECU measures
current through the wire and uses this information to calculate the mass of air entering the engine.
