Commencement Of Pre-Injection Cycle
The pump piston is pressed down by the injection cam via the roller-type rocker arm, and thus displaces the fuel from the high-pressure chamber into the fuel supply line. The PCM initiates the injection cycle. For this purpose, the PCM activates the injector solenoid valve. The solenoid valve stem is pressed into the seat and closes off the path from the high-pressure chamber to the fuel supply line. As a result, pressure begins to build up inside the high-pressure chamber. At 180 bar, the pressure is greater than the force of the injector spring. The injector needle is lifted and the pre-injection cycle commences.