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 engine's operational characteristics. The operating maps influence the engine's performance.
The ISM consists of two main components, the control computer (hardware) and the flash file. The control computer consists of a microprocessor and of electronic circuitry. The flash file contains the engines operational characteristics. The operating maps influence the option for gas blending.
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. Actual engine rpm is monitored by the engine speed/timing sensor.
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.
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 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. Cold mode is activated whenever the engine coolant temperature falls below a predetermined value.