MIRROR 3170089 - Caterpillar

Controlling the Engine RPM
The engine rpm is controlled by governing of the fuel that is provided to the engine. The electronic control module uses information from these sources to calculate the desired rpm:
Control switches for the power take-off
Throttle position sensor
Engine speed sensorThe electronic control module calculates the desired fuel rack position. These variables are included in the calculation:
Data for the fuel map in the personality module
The desired engine rpm minus the actual engine rpm
The fuel ratio control rack limit and the rated rack limit that is stored in the personality moduleTo move the rack, the electronic control module adjusts the voltage of a signal to the interface module (mechanical unit injection). The interface module adjusts the current to the rack actuator. To determine the actual position of the rack, the engine control module interprets a signal from a rack position sensor.Power Take-off Mode
The power take-off mode is activated by a switch. Closing the switch enables the power take-off mode. When the mode is enabled, the engine rpm can be increased or decreased with a speed switch.Control of the Fuel to Air Ratio
The fuel ratio control rack limit is a limit of the fuel to air ratio. This limit is used for control of emissions. The electronic control module receives information from the sensor for inlet manifold air pressure (boost pressure). An increase in the inlet manifold air pressure indicates that more combustion air is available. When this occurs the rack limit is increased in order to provide more fuel for combustion.The fuel ratio control rack limit is programmed at the factory. This limit can be reprogrammed by the customer.Rated Rack Limit
The rated rack is a rack limit that is based on the engine's power rating. The rated rack determines the maximum values for power and torque for the specific engine.The rated rack limit is programmed at the factory.Cold Start Strategy
The electronic control module uses information from a coolant temperature sensor to activate cold mode operation.Cold mode operation is activated when the coolant temperature is below 60 °C (140 °F). The rack position is limited during engine start-up. The following occurrences deactivate cold mode operation:
The engine rpm increases to more than 1200 rpm.
The engine has operated for five minutes.