Differential Pressure Regulator: Description and Operation

Fig. 18 Fuel Distributor with Differential Pressure Regulator:

The differential pressure regulator replaces the warm up regulator and the frequency valve found on CIS Lambda systems. The pressure regulator Fig. 18, is mounted on the fuel distributor. It acts as a pressure regulator which operates as a plate valve. The position of the plate can be varied causing a differential pressure change between the lower chamber and the actuator, and therefore, a mixture change.
The signal controlling the pressure regulator comes from the ECU, based on the signals from the various sensors (temp, engine speed, etc.). With the engine running, a constant system pressure of 5.2 - 5.6 bar (75 - 82 psi) is supplied at the fuel inlet. The pressure regulator is adjusted by variations of current thereby determining the control pressure to the fuel distributor control plunger. The corresponding pressure change in the lower chamber causes movement of the diaphragm, and influences the fuel volume flowing to the injectors.