Airflow Meter
All intake air is drawn through the airflow meter. See Fig 2 . The meter contains a tunnel with a measuring flap and dampening flap. The measuring flap swings in with air stream against pressure of a spiral spring and is connected to a potentiometer.
The potentiometer transmits an electrical signal determined by measuring flap position to inform ECU of engine load. At idle, the measuring flap is almost closed due to spring pressure.
The potentiometer within the airflow meter prevents loss of engine power during engine load or sudden acceleration (along with engine speed and coolant temperature) by signaling the ECU of necessary enrichment and timing requirements.
An idle air by-pass receives airflow through a small hole, the size of which is controlled by the idle mixture screw. This adjustable air by-pass influences CO levels at low engine speeds.