ELECTRONIC UNIT INJECTOR Solenoid Control Valve Control Unit Body Filter O-RINGS High Pressure Fuel Vent Intermediate Valve Sleeve Rod Fuel Return Needle Valve Nut Nozzle Fig. 31 Injector Assembly (Cutaway) The Electronic Unit Injector delivers the fuel input into each cylinder. The unit injector receives high-pressure fuel continuously from the high- pressure rails. The unit injector does not need to make pressure, therefore, there is no camshaft driven mechanism requiring adjustment or tune-up. The amount of fuel and timing is controlled by DDECIV. DDECIV controls the fuel flow in the injector by sending a signal to the injector solenoid.
The control valve is spring loaded in the closed position and opens when the solenoid is energized. Each injector has its own calibration code, which is factory determined and stamped on the injector identification plate (Fig. 32 and Fig. 33). The calibration code can be any number from 00 to 99 (Fig. 34). The calibration code is entered into DDECIV with the DDR reader or DDDL, so that DDECIV can balance each injector for uniform fuel output and performance. Page 31