SHIELD 8W9227 - Caterpillar

Electronic Controls
Electronic Control Module
The ECM consists of two main components, the control computer (hardware) and the flash file (software). The control computer consists of a microprocessor and electronic circuitry. The flash file contains the engines operational characteristics. The operating maps influence the engines performance.Engine Governor
The engine ECM governs engine speed. The engine ECM and the flash file work together by controlling the amount of fuel that is delivered by the injectors. Desired engine rpm is determined by the throttle position sensor signal and certain sensor readings. Diagnostic codes may derate the engine. Actual engine rpm is measured by the engine speed/timing signal.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 V 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 V signal, the ECM controls the engine speed.Injection timing depends on the following conditions: 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.