The 3100 HEUI Diesel Truck Engines use a Hydraulic Electronic Unit Injector fuel system. The injection pump, fuel lines and nozzles required for fuel injection in mechanical Caterpillar engines have been replaced with a hydraulic electronic unit injector in each cylinder. Some mechanical drive components, cam lobes, lifter, push rod, and rocker arms required for fuel injection in mechanical or Electronic Unit Injector Caterpillar engines have been replaced with a high pressure oil system.
A solenoid on each injector controls the amount of fuel delivered by the injector. A gear-driven axial piston pump raises the normal engine operating oil pressure to injector actuation pressure levels required by the injectors. An Electronic Control Module (ECM) sends a signal to the injection actuation pressure control valve to control injection pressure, and another signal to each injector solenoid to inject fuel.
The 3100 HEUI Diesel Truck Engines electronic system consists of the Electronic Control Module (ECM), Engine Sensors, Injection Actuation Pressure Control Valve, and Vehicle Interface. The ECM is the computer which controls the 3100 HEUI engine. The Personality Module in the ECM contains the software which controls how the ECM behaves (the personality module stores the operating maps that define power rating, torque curves, rpm, etc).
The Electronic Control system on the 3100 HEUI engine serve as the engine governor. The Electronic Control system determines when and how much fuel to deliver to the cylinders, as well as injection pressure based on the actual and desired conditions at any given time during starting and operation.
The basic governor operation considers the desired and actual conditions, and then takes action to best accommodate the desired conditions.
The desired conditions are typically the position of the accelerator pedal, desired vehicle speed when in cruise control, or desired engine rpm when in PTO control. The actual conditions are based on current operating conditions such as coolant temperature, load conditions, etc.