RING 1S0668 - Caterpillar

Ambient Based Rating
The ambient based rating feature provides flexibility for Separate Circuit Aftercooler (SCAC) temperature, so the engine is NOT shutdown for reaching temperatures exceeding the purchased rating. The air/fuel ratio and load factor are automatically adjusted based on the SCAC temperature.Ambient based rating feature:
Load calculation, load limiting, and fuel correction factor are a function of the Intake Manifold Air Temperature (IMAT).
Ambient based rating is enabled by default on all 32C and 43C software and cannot be disabled in Cat® Electronic Technician (ET).Control System
The following components are included in the control system:
An Electronic Control Module (ECM) and an emergency stop button in an engine-mounted junction box
Optional remote control panel with either an Operator Control Panel (OCP) or Human Machine Interface (HMI)
Integrated Sensing Module (ISM)
Fuel metering valve
Gas Shutoff Valve (GSOV)
Ignition system that is controlled by the ECM
Detonation sensor for each two cylinders
A system for prelube or postlube that includes a solenoid and prelube pump
Actuators that are hydraulically actuated and electronically controlled for the air choke and the exhaust bypass (wastegate)
A system for cranking that includes the solenoid and starting motor
Air/Fuel pressure module (G3616)The ECM controls most of the functions of the engine. The module is an environmentally sealed unit that is in an engine-mounted junction box. The ECM monitors various inputs from sensors to activate relays, solenoids, and so on, at the appropriate levels. The ECM supports the following five primary functions:
Governing of the engine
Control of ignition
Air/fuel ratio control
Start/stop control
Monitoring of engine operationThe ECM does not have a removable personality module. The software and maps are changed by using the Cat ET to flash program a file.Governing of the Engine RPM
Desired engine speed is determined by these factors: status of the idle/rated switch, status of the desired speed input (analog voltage, 4 mA to 20 mA, or CAN) and of parameters that are programmed into the software. Actual engine speed is detected via a signal from the engine speed/timing sensor. Parameters such as idle speed and governor gain can be programmed with Cat ET, but the governor gain should not be programmed.The ECM monitors the actual engine speed. The ECM calculates the difference between the actual engine speed and the desired engine speed. The ECM controls the fuel metering valve to maintain the desired engine speed. The fuel metering valve is located in the gas line after the GSOV.If actual engine speed is less than desired engine speed, the ECM commands the fuel metering valve to move toward the open position to increase the fuel flow. The increase of fuel accelerates the engine speed.The speed governor gain adjustments Proportional (P) and Integral (I) are available in Cat ET. The speed governor gain adjustment Derivative (D) does not exist in the software.The air/fuel ratio control gains adjustment is not available in Cat ET for Adem 4 (A4) controlled engines.G3606, G3608, and G3612
The fuel flow is controlled by the desired air/fuel ratio until 500 rpm.
The air