ROD AS 4787551 - Caterpillar

Fuel Heaters
Fuel heaters prevent the waxing of the fuel in cold weather. The engine does not dissipate enough heat in order to prevent waxing during cold weather conditions. Heaters that are not thermostatically controlled can heat the fuel in excess of 65 °C (149 °F). High fuel temperatures can have the following effects:
Reduced engine efficiency
Fuel pump damage
Premature wearNote: Fuel heaters without thermostatic controls must never be used.The two types of fuel heaters that can be used: thermostatically controlled and self-adjusting.Electronic Controls
There are two major components of the electronic control system that are necessary in order to provide control of the mechanical electronic unit injectors:
ECM
Personality module (storage for the ECM flash file)The ECM is the computer that is used to provide control for all aspects of engine operation. The personality module contains the software that defines the characteristics of the engine control. The personality module contains the operating maps. The operating maps define the following characteristics of the engine:
Horsepower
Torque curves
Engine speed (rpm)
Other characteristicsThe ECM, the personality module, the engine sensors, and the unit injectors work together in order to control the engine. Neither of the four can control the engine alone. The ECM maintains the desired engine speed by sensing the actual engine speed. The ECM calculates the amount of fuel that needs to be injected in order to achieve the desired engine speed.Fuel Injection
The ECM controls the amount of fuel that is injected by varying the signal to each of the unit injectors. The unit injectors will inject fuel only while the unit injector solenoid is energized. The ECM sends a 105 volt signal to the solenoid in order to energize the injector solenoid. By controlling the timing of the 105 volt signal, the ECM controls injection timing. By controlling the duration of the 105 volt signal, the ECM controls the amount of fuel that is injected.The ECM sets certain limits on the amount of fuel that can be injected. The FRC fuel position is a limit that is based on boost pressure in order to control the fuel air mixture for the emission control. When the ECM senses an increase in the boost pressure, the ECM increases the FRC fuel position. The rated fuel position is a limit that is based on the horsepower rating of the engine. The rated fuel position is similar to the rack stops and the torque spring on a mechanically governed engine. The rated fuel position provides the horsepower and the torque curves for a specific engine family. The rated fuel position provides the horsepower and the torque curves for a specific horsepower rating. The limits are programmed by the factory into the personality module. The limits are not programmable in the field.The injection timing relies on the following engine parameters: engine speed, engine load and other engine data. The ECM senses the top center position of number one cylinder from the signal that is provided by the engine speed/timing sensors. The ECM decides when the injection should occur relative to this