Diesel Models
ELECTRO-HYDRAULIC INJECTORElectro-Hydaulic Injector, Part 1:
Electro-Hydaulic Injector, Part 2:
The electro-hydraulic injector is composed of three major components: The oil control, pressure amplification, and the nozzle assembly. The injector uses two 48-volt at 20-amp coils to control a spool valve that directs oil flow in and out of the injector. The fuel injector has a self-extracting hold-down clamp.
ELECTRO-HYDRAULIC INJECTOR AMPLIFIER PISTON
The high pressure oil flows from the oil rails into an electro-hydraulic injector amplifier piston located in the injector. Oil entry and exit to and from the amplifier piston is controlled by a coil-operated spool valve.
ELECTRO-HYDRAULIC INJECTOR FUEL PLUNGER
The electro-hydraulic injector fuel plunger is located in the injector and is driven by the amplifier piston. The fuel plunger injects fuel into the combustion chamber at pressures of up to 196,500 kPa (28,500 psi) through the nozzle assembly. Fuel is supplied to the injector at approximately 345 kPa (50 psi) through fuel rails in the cylinder heads.
ENGINE TIMING
The PCM commands the fuel quantity. The FICM controls the duration of the injection event and is shown as parameter ID (PID) "FUELPW" on the scan tool.
The PCM controls the injection pressure and fuel volume by varying the injection oil pressure with the injection pressure regulator (IPR). The command to the IPR is a 12-volt, pulse width modulated (PWM) signal (controlled on the ground side).
The injection oil pressure command is shown as PID IPR which is the percentage ON of the pulse width modulated signal. Injection oil pressure is shown as PID ICP.
The PCM uses camshaft position (CMP) and crankshaft position (CKP) input signals to calculate engine speed and position. The PCM conditions both input signals and supplies the FICM with the CMP and CKP output signals. The FICM uses CMP and CKP output signals to determine the correct sequence for injector firing. The PCM sends information about the fuel demand, engine oil temperature (EOT) and injection control pressure (ICP) through CAN to the fuel injection control module (FICM). The FICM uses this information to calculate the injection cycle.