And for the FRP sensor

The fuel rail pressure control valve is incorporated into the high pressure fuel pump. The control valve regulates the fuel pressure within the fuel rail and is controlled by the ECM (engine control module) . The control valve is a PWM (pulse width modulation) controlled solenoid valve.

When the solenoid is de-energized, an internal spring holds an internal valve closed. At fuel pressure of 100 bar (1450 lbf/in²) or higher, the force of the spring is overcome, opening the valve and allowing fuel pressure to decay into the fuel return pipe. When the pressure in the fuel rail decays to approximately 100 bar (1450 lbf/in²) or less, the spring force overcomes the fuel pressure and closes the valve. When the ECM (engine control module) energizes the solenoid, the valve is closed allowing the fuel pressure to build. The pressure in the fuel rail in this condition can reach approximately 1600 bar.

The ECM (engine control module) controls the fuel rail pressure by operating the control valve solenoid using a PWM (pulse width modulation) signal. By varying the duty cycle of the PWM (pulse width modulation) signal, the ECM (engine control module) can accurately control the fuel rail pressure and hence the pressure delivered to the injectors according to engine load. This is achieved by the control valve allowing a greater or lesser volume of fuel to pass from the high pressure side of the pump to the un-pressurized fuel return line, regulating the pressure on the high pressure side.

The fuel rail pressure control valve receives a PWM (pulse width modulation) signal from the ECM (engine control module) of between 0 and 12V. The ECM (engine control module) controls the operation of the control valve using the following information to determine the required fuel pressure:

Excellent info, bellautos - and thanks for keeping it non-commercial too  

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