821316 1 Mariner CAM-SHIFT

Electronic Controls
The engine's electronic system consists of the ECM, the engine sensors, the injection actuation pressure control valve, and the vehicle interface. The ECM is a computer that controls the operation of the engine. The personality module is the software for this computer. The personality module contains the operating maps. The operating maps define the following characteristics of the engine:
Horsepower
Torque curves
Engine speed (rpm)Engine Governor Controls
The electronic controls that are on the engine serve as the engine governor.The electronic controls determine the timing, the injection pressure and the amount of fuel that is delivered to the cylinders. These factors are based on the actual conditions and the desired conditions at any given time during starting and operation.The governor uses the accelerator pedal position sensor to determine the desired engine speed. The governor compares the desired engine speed to the actual engine speed. The actual engine speed is determined through interpretation of the signals that are received by the ECM from the engine speed/timing sensors. If the desired engine speed is greater than the actual engine speed, the governor injects more fuel in order to increase engine speed.
Illustration 1 g01120999
Typical example
The desired engine speed is typically determined by one of the following conditions:
The position of the accelerator pedal
The desired vehicle speed in cruise control
The desired engine speed in Power Take-Off (PTO)Timing Considerations
Once the governor has determined the amount of fuel that is required, the governor must determine the timing of the fuel injection. Fuel injection timing is determined by the ECM after considering input from the following components:
Coolant temperature sensor
Air temperature sensor for the inlet manifold
Atmospheric pressure sensor
Boost pressure sensorThe ECM adjusts timing for optimum engine performance, for fuel economy, and for the control of white smoke. Actual timing and desired timing cannot be viewed with Caterpillar Electronic Technician (ET). The ECM determines the location of top center of the number one cylinder from the signal that is provided by the engine speed/timing sensors. The ECM determines when injection should occur relative to top center. The ECM then provides the signal to the injector at the desired time.Fuel Injection
The ECM controls the amount of fuel that is injected by varying the signals to the injectors and by controlling actuation pressure. The injectors will pump fuel only if the injector solenoid is energized. The ECM sends a high voltage signal in order to energize the solenoid. The injector solenoid moves a seated pin that allows the actuation pressure to hold the nozzle check closed. The movement of the seated pin also causes the spool valve to open. This allows the actuation pressure to act on the piston and on the plunger. This produces injection pressure. The hydraulic force that holds the nozzle check closed quickly dissipates and the injection pressure opens the nozzle check. By controlling the timing and the duration of the high voltage signal, the ECM can control the following aspects of injection:
Injection timing
Fuel delivery
Injection rate shapeThe ECM controls injection pressure by controlling the Injection Actuation Pressure Control Valve (IAPCV). The IAPCV regulates the unit injector hydraulic pump's outlet pressure by controlling the pump's flow regulation system.The personality module inside the ECM establishes certain limits on the amount of fuel that can be injected. The "FRC Fuel Limit" is a limit that is based on the boost pressure. The "FRC Fuel Limit" is used to control the air/fuel ratio for control of emissions. When the ECM senses a higher boost pressure, the ECM increases the "FRC Fuel Limit". A higher boost pressure indicates that there is more air in the cylinder. When the ECM increases the "FRC Fuel Limit", the ECM changes the control signal to the injector in order to allow more fuel into the cylinder.The "Rated Fuel Limit" is a limit that is based on the power rating of the engine and on the engine rpm. The "Rated Fuel Limit" is similar to the rack stops and the torque spring on a mechanically governed engine. The "Rated Fuel Limit" provides the power curves and the torque curves for a specific engine family and a specific engine rating. All of these limits are determined at the factory. These limits are part of the personality module and the limits cannot be changed.Injection Actuation Pressure Control System
The ECM controls the fuel injection delivery and injection pressure by controlling oil pressure to the fuel injectors. The pressure of the oil in the high pressure oil manifold is controlled by the ECM through control of the IAPCV. The IAPCV regulates the unit injector hydraulic pump's outlet pressure.The ECM monitors the pressure in the high pressure manifold through the injection actuation pressure sensor. The injection actuation pressure sensor is located in the top of the manifold on the left side of the engine. The injection actuation pressure sensor's signal is compared by the ECM to the desired injection actuation pressure. The injection actuation pressure sensor's signal is based on sensor inputs. The sensor inputs are used to adjust the control current to the IAPCV in order to adjust the oil pressure in the high pressure manifold.High pressure oil is routed from the unit injector hydraulic pump to the high pressure manifold through a steel tube. The oil is routed to each injector through the high pressure oil manifold. All injectors have a constant supply of oil while the engine is running. Disabling the electrical signal to the injector solenoid does not interrupt the oil flow that is available to the fuel injector.Cold Mode
The engine operates in cold mode when the coolant is cold. Engine performance is reduced while the engine is in cold mode. C7 engines operate in cold mode when the coolant temperature is below 18 °C (64 °F). C9 engines operate in cold mode when the coolant temperature is below 64° C (147° F). A status flag on Cat ET indicates that the engine is operating in cold mode.Customer Parameters and Engine Speed Governing
A unique feature with electronic engines is customer specified parameters. These parameters allow the vehicle owner to fine tune