Hot-Film Mass Airflow Sensor

The hot-film mass airflow sensor senses mass of intake air. Sensor is located in air intake channel between throttle body and air cleaner. See Figure . The engine control module needs air mass measurement to control minimum fuel injection quantity, warm-up enrichment, acceleration enrichment, ignition during warm-up, ignition at Wide Open Throttle (WOT), catalyst warm-up, Lambda control, charcoal canister purging, camshaft adjustment, overheat protection, intake air temperature correction, and transmission overload protection.

The hot-film sensor is clamped inside the metering pipe. Sensor is constructed from a ceramic substrate upon which heater resistor, sensor resistor, air temperature sensor, and compensating resistor are measured. A hybrid electronic switch and power converter are located in the electronics housing. A heat sink is attached to the outside of the electronics housing. The electronics housing with metering pipe is inserted into the main housing. A protective screen calms turbulence so intake air flows evenly around the hot-film sensor.