808571A96 Mercury DECAL SET

Electronic Ignition System (EIS)
The Caterpillar EIS provides variable ignition timing that is sensitive to detonation. The EIS consists of the following components:
EIS control module
Ignition transformers
Speed/Timing sensor
Manifold air pressure sensor (MAP)
Detonation sensorsEach cylinder has an ignition transformer that is located under the valve cover for the cylinder. To initiate combustion, the control module sends a pulse of approximately 190 volts to the primary coil of each ignition transformer at the appropriate time and for the appropriate duration. The transformers step up the voltage in order to create a spark across the spark plug electrode.Detonation sensors monitor the engine for excessive detonation. The engine has two detonation sensors. Each sensor monitors one cylinder bank. The sensors generate data on vibration that is processed by the control module in order to determine detonation levels. If detonation reaches an unacceptable level, the control module retards the ignition timing of the cylinders. If retarding the timing does not limit detonation to an acceptable level, the control module shuts down the engine.The ignition is enabled via an input on the control module. The input is activated by a control system that is provided by Caterpillar or by the customer.The control module provides extensive diagnostics for the ignition system. The control module also contains an input for ignition timing in order to allow operation with alternate fuels such as propane that require a timing offset.Optional Electronic Systems
Optional electronic systems provide additional capabilities and features. The systems that may be installed depend on the application.
Air/fuel ratio control
Status Control Module (SCM)
Other systems that are provided by Caterpillar or by the customerAir/Fuel Ratio Control
The engine may be equipped with an air/fuel ratio control system. The system provides the following capabilities:
Control of exhaust emissions
Adjustment for changes in the fuel BTU
Engine speed governingThe system consists of the following components:
Electronic Control Module (ECM)
Oxygen sensor
Oxygen buffer
Speed sensor
Inlet manifold pressure sensor
Inlet manifold temperature sensor
Fuel valve
Throttle actuator
Input switchesSome of the components are located in a remote control panel that is connected to the engine via a wiring harness.The air/fuel ratio control consists of two subsystems: air/fuel ratio control and engine speed governing.Air/Fuel Ratio Control
The ECM provides control of the air/fuel mixture for performance and efficiency at low emission levels. The control compensates for changes in the BTU of the fuel in order to maintain desired emission levels.The following steps describe the basic operation:
The ECM determines the desired flow rates for the air and the fuel. The flow rates are determined by these factors:
Desired engine speed
Actual engine speed
Calculated engine load
The ECM sends a signal to the fuel metering valve and a signal to the governor.
The ECM monitors the amount of oxygen in the exhaust gas via the oxygen sensor. The ECM adjusts the signal for the flow of air and fuel in order to achieve the desired level of exhaust emissions.This process is repeated continuously during engine operation unless the AFR control has been disabled. The air/fuel ratio control may be disabled with the Digital Diagnostic Tool (DDT). This aids in troubleshooting the system.The air/fuel ratio control communicates with the EIS via the Cat data link. Sensor information and control information are passed between the two systems via the Cat data link.Engine Speed Governing
The ECM uses sensors, switches, and the throttle actuator in order to govern the speed of the engine.Desired engine speed is determined by the status of the idle/rated switch, the desired speed input, and programmable parameters.The source of the desired engine speed depends on the application. The input may be from a potentiometer, a pressure module, or an electronic device.Inside the ECM, the desired engine speed is compared to the actual engine speed. The ECM uses gains in order to provide stable operation. The ECM issues a throttle command to the throttle actuator.The throttle actuator is electrically controlled and hydraulically actuated. The throttle position is controlled in open loop mode: there is no feedback for the throttle position. The actual throttle position can be viewed on a mechanical pointer that is built into the mechanism of the throttle.Status Control Module (SCM)
The SCM includes the following features:
Control of starting the engine and stopping the engine
Basic engine protection
A display of the status of certain parameters
Shutdown indicators
Diagnostic informationWhen the SCM receives a signal to start the engine, the SCM activates the fuel system and the starting motor. The SCM also sends a command to the EIS control module in order to begin the ignition. When the engine rpm reaches the crank termination speed, the starting motor is disengaged. The SCM will sequentially display the following parameters in two second increments: service hours, engine rpm, battery voltage, engine oil pressure and engine oil temperature. The SCM also monitors the engine for faults.The SCM protects the engine from certain faults. For example, the SCM will shut down the engine if the oil temperature is above the setpoint.The SCM displays certain operating parameters. For example, the temperature of the oil can be displayed on the module's indicator.The SCM also has light emitting diodes that indicate an engine shutdown.The engine will operate until the SCM receives a shutdown signal. The shutdown signal can come from a switch or from the EIS control module. When the SCM shuts off the fuel supply, the SCM also sends a command to the EIS control module in order to terminate the ignition.Engine Monitoring and Protection
The engine may be equipped with a system that provides additional features. The system that is installed depends on the application. The system may communicate with the EIS and the air/fuel ratio control via the Cat data link. The system may provide some of the following features or all of the following features:
Control of starting the engine and stopping the engine
Basic engine protection
A display of the status of certain operating parameters
Diagnostic informationThese features may be provided by these systems:
Status Control Module
Electronic Modular Control Panel (EMCP)Start/Stop Control
If the system provides start/stop control of the engine, the system sends a command to the EIS control module. The command enables the ignition and the command disables the ignition.If the system does not