The amount of air entering your engine is a mesaurable value.
This undertaken either by a moving vane air sensor or more commonly a MAF or mass airflow unit.
The early MAFs were literally a heated wire,the amount of air was detected by the level of current needed to maintain the wires temperature.
All a bit hit and miss and prone to a lot of failures. Todays MAFs use thin film technology giving far quicker responses to changing air flow conditions
This undertaken either by a moving vane air sensor or more commonly a MAF or mass airflow unit.
The early MAFs were literally a heated wire,the amount of air was detected by the level of current needed to maintain the wires temperature.
All a bit hit and miss and prone to a lot of failures. Todays MAFs use thin film technology giving far quicker responses to changing air flow conditions