Bosch L-Jetronic Electronic Fuel Injection

Fig. 3 Airflow meter:

The airflow meter supplies a voltage signal to the control unit that varies with the amount of air passing through it. The incoming air pushes against a sensor flap. The position of the sensor flap is transmitted electrically to a potentiometer, Fig. 3. A compensation flap attached to the sensor flap compensates for back pressure pulsations so that any back pressure does not affect airflow measurement. The sensor flap is equipped with a check valve that protects the sensor from damage during back pressure peaks.