KIT-SEAL 1799634 - Caterpillar

System Operation
Electronic Controls
The electronic system consists of the ECM, the engine sensors and the vehicle interface. 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 curves
RPM
Other characteristicsEngine Governor
The ECM serves as the engine governor.The ECM determines the timing and the amount of fuel that is delivered to the cylinders. This is based on the actual conditions and the desired conditions at any given time.The governor uses the accelerator pedal position sensor to determine the desired engine speed. The governor compares the desired engine speed to the actual engine speed. The actual engine speed is determined through a signal from the primary engine speed/timing sensor. If the desired engine speed is greater than the actual engine speed, the governor injects more fuel in order to increase engine speed.The desired engine speed is typically determined by one of the following conditions:
The position of the accelerator pedal
The desired vehicle speed in cruise control
The desired engine rpm in PTO controlTiming Considerations
Once the governor has determined the amount of fuel that is required, the governor must determine the timing of the fuel injection. Fuel injection timing is determined by the ECM after receiving input from the following components:
Coolant temperature sensor
Intake manifold air temperature sensor
Barometric pressure sensor
Boost pressure sensorAt start-up, the ECM determines the top center position of the number 1 cylinder from the signal for the secondary engine speed/timing sensor. After start-up, the ECM determines the top center position of the number 1 cylinder from the primary engine speed/timing sensor. The ECM determines when fuel injection should occur relative to the top center position and the ECM provides the signal to the injector at the desired time. The ECM adjusts timing for the optimum engine performance, the optimum fuel economy and the optimum control of white smoke.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 ECM can control the amount of fuel that is injected.The flash file sets certain limits on the amount of fuel that can be injected. The "FRC Fuel Limit" is a limit that is based on the boost pressure. The "FRC Fuel Limit" is used to control the air/fuel ratio for control of emissions. When the ECM senses a higher boost pressure, the ECM increases the "FRC Fuel Limit". A higher boost pressure indicates that there is more air in the cylinder. When the ECM increases the "FRC Fuel Limit", the ECM allows more fuel into the cylinder.The