•  The electromagnetic valve controls inflow/outflow of fuel to the command chamber by opening and closing according to an ON/OFF signal received from the PCM.

―  When the electromagnetic valve is not energized, the two way valve is pushed down, closing the command chamber outflow orifice, and causing the pressurized fuel from the fuel distribution pipe to fill the command chamber. Due to this, the nozzle connected to the command piston is closed and injection does not occur.

―  When electromagnetic valve energization begins the two-way valve is pulled upwards, opening the command chamber outflow orifice and fuel outflow occurs. As fuel outflow occurs, the command chamber pressure decreases, drawing the command piston and the nozzle upward, and injection begins. Also, the fuel passed through the outflow orifice is used to lubricate the command piston and the fuel pressure is used to lift the piston up allowing injection to begin. As energization continues the nozzle is opened even more, providing maximum injection rate. When energization of the electromagnetic valve ends, the two-way valve once again moves down and the nozzle is closed instantaneously. Since the valve can be repeatedly energized any number of times, multiple pilot injection is made possible.