The ECM 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 engine's operational characteristics. The operating maps influence the engine's performance.
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 by certain sensor readings. Diagnostic codes may derate the engine. Actual engine rpm is detected 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. By controlling the timing and duration of the 105 volt 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 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 flash file inside the engine ECM sets certain limits on the amount of fuel that can be injected. The FRC limit is a limit that is based on the boost pressure. The boost pressure is calculated as the difference in pressure between atmospheric pressure and turbocharger outlet pressure. The FRC limit is used to control the air/fuel ratio for control of emissions. When the engine ECM senses a higher boost pressure, the engine ECM increases the FRC limit. A higher boost pressure indicates that there is more air in the cylinder. When the engine ECM increases the FRC limit, the engine ECM allows more fuel into the cylinder.
The rated fuel position is a limit that is based on the power 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 determines maximum power and torque values for a specific engine family and a specific rating. The rated fuel position is programmed into the flash file at the factory.
Engine Starting and Stopping Procedures
1. The generator control module will receive one of the following start signals:
- The operator places the control in the RUN mode.
- The operator places the control in the AUTO mode and the remote initiate input becomes active.
- The operator places the control in the AUTO mode and a start command is sent via the data link.
2. The generator control module performs the following system checks:
- No system faults are present.
- All previous shutdown faults have been reset.
- The engine is not already running.
- If the prelube (if equipped) is not complete, the generator control module will not crank the engine.
3. The generator control module begins the following cranking sequence:
- Activate the Starting Motor Relay (SMR).
- A start signal is sent to the engine ECM via the Cat Data Link and the fuel control relay is activated.
4. The generator control enables cranking the engine until the cycle crank time reaches the setpoint for total crank time or until the engine starts.
5. The generator control module deactivates the SMR when the engine speed reaches the setpoint for crank terminate speed.
1. The generator control module receives one of the following engine stop signal:
- The operator places the control in the STOP mode.
- The operator places the control in the AUTO mode and the remote initiate input becomes inactive.
- The generator control module begins the cooldown period. Place the generator control in the STOP mode in order to bypass the cooldown. "Press Enter To Bypass" and "Press Escape To Continue" will be shown on the display.
2. After the cooldown period, the generator control module sends a shutdown signal to the engine ECM. The engine ECM deactivates the fuel control relay which shuts down the engine.