COVER 8N6984 - Caterpillar

The engine is designed for electronic control of most engine operating functions. The electronic system consists of an Electronic Control Module (ECM), the wiring harnesses, switches, sensors, and Electronic Unit Injectors (EUI). The ECM monitors parameters during engine operation. The ECM supplies signals to the (EUI). The ECM signals control the engine operation. Electronic Controls
Electronic Control Module
The ECM consists of three main components, the control computer (hardware), the flash file (software) and the configuration file. The control computer consists of a microprocessor and electronic circuitry. The flash file is the software for the control computer which contains the operating maps that define power and torque curves. The configuration file contains the adjustable settings for the engine monitoring system. The configuration file also allows the customer to enable optional equipment. The customer can fine tune the engine by modifying the settings in the configuration file. The engine is shipped from the factory with default values for these settings.Engine Governor
The engine ECM governs engine speed. Desired engine rpm is determined by the throttle position sensor signal and certain sensor readings. Diagnostic codes may be accompanied by a reduction in the available power from the engine. The reduction in power is typically called an engine derate. Actual engine rpm is measured by the engine speed/timing sensor.Fuel Injection
The engine ECM controls the timing and the duration of the fuel that is injected. The engine ECM varies the signals to the fuel injectors. Fuel is injected only while an injector solenoid is energized by a 105 volt signal from the engine ECM. The timing of the injection signal determines the engine timing. The length of the injection signal determines engine speed. By controlling the timing and duration of the 105 volt signal, the ECM controls the engine speed.Injection timing depends on the desired engine rpm and load. The ECM detects the top center of each cylinder. The ECM sends an injection signal at the desired time.Cold Cylinder Cutout
During a cold start or extended periods at low idle, the engine ECM will automatically turn off one unit injector at a time in order to determine if the cylinder is firing. If the ECM determines that the cylinder is not firing, the ECM turns off the unit injector. If the ECM determines that the cylinder is firing, the ECM turns on the unit injector. This strategy improves engine starting. This strategy reduces the following: white smoke, the use of ether injection and warm-up time.Cold Mode Operation
Cold mode operation automatically stops fuel injection to cylinders that are not firing. Cold mode operation has the following benefits: increased startability, reduced warm up period and reduced white smoke. The cold cylinder cutout strategy is activated whenever the engine coolant temperature falls below 63 °C (145 °F) and the following conditions are met:
An engine without the ether option has been running for ten seconds.
Ether injection has been completed for three seconds.
The engine has been idling for ten minutes.The engine will exit the cold cylinder cutout strategy for ten minutes