RING 8H3497 - Caterpillar

System Operation
The engine utilizes a Hydraulic Electronic Unit Injector (HEUI) fuel system. A solenoid on each injector meters the amount of fuel that is delivered by the injector. An axial piston pump that is referred to as the unit injector hydraulic pump pressurizes oil in order to activate the injector. An Electronic Control Module (ECM) sends a signal to the injection actuation pressure control valve in order to control injection pressure. Another electrical signal is sent to each injector solenoid in order to inject fuel.Electronic Controls
The electronic system for the engine consists of the ECM, the wiring harness, the engine sensors, the switches, the injection actuation pressure control valve, the unit injector hydraulic pump, the HEUI injectors and the interface for a particular application. The ECM is the computer. The flash file is the software for the computer. The flash file contains the operating maps. The operating maps define the following characteristics of the engine:
Horsepower
Torque curvesThe ECM determines the timing and the amount of fuel that is delivered to the cylinders. This determination is based on the actual conditions and the desired conditions at any given time.The ECM compares the desired engine speed to the actual engine speed. The actual engine speed is determined via a signal from the engine speed/timing sensor. If the desired engine speed is greater than the actual engine speed, the ECM injects more fuel in order to increase the actual engine speed.Fuel Injection
The ECM controls the amount of fuel that is injected by varying the signals to the injectors. The injectors will pump fuel only if the injector solenoid is energized. The ECM sends a high voltage signal to the solenoid. This high voltage signal energizes the solenoid. By controlling the timing and the duration of the high voltage signal, the ECM can control injection timing and the amount of fuel that is injected.The ECM limits engine power during cold mode operation and the ECM modifies injection timing during cold mode operation. Cold mode operation provides the following benefits:
Increased cold weather starting capability
Reduced warm-up time
Reduced white smokeCold mode is activated whenever the engine coolant temperature falls below 18 °C (64 °F). Cold mode remains active until the engine coolant temperature rises above 20 °C (68 °F) or until the engine has been running for 14 minutes.The flash file inside the ECM sets certain limits on the amount of fuel that can be injected. The "FRC Fuel Limit" is used to control the air/fuel ratio for control of emissions. The "FRC Fuel Limit" is