Modulating piston displacement sensor and quantity adjuster, checking: Notes
WARNING: This page is about a different car, the 1999 Volkswagen Jetta, 1998 Volkswagen Jetta, and 1997 Volkswagen Jetta. However, it is still accessible from the selected car via links, so may be relevant.
The quantity adjuster -N146- is an electro-magnetic positioner, controlled by the Diesel Direct Fuel Injection (DFI) ECM via duty cycle (on-off ratio). The eccentric shaft on the quantity adjuster moves the modulating piston (on the high-pressure piston), regulating the amount of fuel injected.
The modulating piston displacement sensor provides the ECM with information on quantity adjuster position, and the ECM then calculates the required amount of fuel for injection.