CYLINDER HEAD GP 3852572 - Caterpillar

System Operation
The 3176B Marine Engines were designed for electronic control. The injection pump, fuel lines and nozzles used in traditional Caterpillar engines have been replaced with an electronic unit injector in each cylinder. A solenoid on each injector controls the amount of fuel delivered by the injector. An Electronic Control Module (ECM) sends a signal to each injector solenoid, to provide complete control of the engine.Electronic Controls
The 3176B Marine Engines electronic system consists of two main components: the Electronics [Electronic Control Module (ECM) and Sensors] and the Personality Module. The ECM is the computer which controls the 3176B engine. The Personality Module contains the software which controls how the ECM behaves (the personality module stores the operating maps that define horsepower, torque curves, rpm, etc). The two must be used together: neither can do anything by itself.The ECM determines a "desired rpm" based on the throttle signal and certain diagnostic codes. The ECM then maintains the desired engine rpm by sensing actual engine rpm and deciding how much fuel to inject in order to achieve the desired rpm.Fuel Injection
The ECM controls the amount of fuel injected by varying signals to the injectors. The injectors will inject fuel ONLY if the injector solenoid is energized. The ECM sends a 100 volt signal to the solenoid to energize it. By controlling the timing and duration of the 100 volt signal, the ECM can control injection timing and the amount of fuel injected.The ECM sets certain limits on the amount of fuel that can be injected. "FRC Fuel Pos" is a limit based on boost pressure to control the fuel to air ratio, for emissions control purposes. When the ECM senses a higher boost pressure (more air into cylinder), it increases the "FRC Fuel Pos" limit (allows more fuel into cylinder). "Rated Fuel Pos" is a limit based on the horsepower rating of the engine. It is similar to the rack stops and torque spring on a mechanically governed engine. It provides horsepower and torque curves for specific engine family and rating. All of these limits are programmed at the factory into the Personality Module and are not programmable in the field.Injection timing depends on engine rpm, load and other operating factors. The ECM knows where top center on cylinder number one is from the signal provided by the engine Speed/Timing Sensor. It decides when injection should occur relative to top center and provides the signal to the injector at the desired time.Caterpillar Engine Monitoring
Caterpillar provides a factory installed Engine Monitoring system. The Caterpillar Engine Monitoring system monitors engine oil pressure, coolant temperature, intake manifold air temperature, and coolant level. The oil pressure, intake manifold air temperature, and coolant temperature sensors are standard on all engines. The Vessel OEM is responsible for providing the coolant level sensor and the associated harness. The coolant level sensor is the only individually selectable component of Caterpillar Engine Monitoring. It is ENABLED or DISABLED through a Customer Programmable Parameter.Caterpillar Engine Monitoring can be programmed to