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. 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.