BEARING 4J2379 - Caterpillar

The Electronic Control Module (ECM) provides control of the air/fuel mixture for maximum performance and for efficiency at low emission levels. The system includes several factors: maps in the ECM, output drivers in the ECM, sensors, and customers input via the Caterpillar Electronic Technician (ET).Refer to Illustration 1 for a diagram of the main components and inputs for the system.
Illustration 1 g06146860
Diagram of the air/fuel ratio control
Required Inputs from the Customer
to control the air/fuel ratio, the control system depends on these inputs from the customer:
Fuel Quality
Engine LoadFuel Quality
Before the initial start-up, a current gas analysis is required. Data from the gas analysis must be entered into Caterpillar Software, LERW4485, "Gas Engine Rating Pro (GERP)". The results are programmed into the ECM.Note: Is important to use the Caterpillar Software, LERW4485, "Gas Engine Rating Pro (GERP)". Use of only the data from the gas analysis can result in incorrect settings.The ECM must have values for the following parameters. The values are entered via the "Configuration" screen of Cat ET:
"Fuel Quality Input Type Configuration"
"Fuel Quality"
"Fuel Quality Sensor LHV Lower Setpoint"
"Fuel Quality Sensor LHV Upper Setpoint"
"Gas Specific Gravity"
"Fuel Specific Heat Ratio"The "Fuel Quality Input Type Configuration" parameter setting will be determined by the consistency of the fuel supply.Select "Configured Value" for engines that run on a consistent fuel supply.Select "4-20 mA" for engines that utilize a 4-20 mA signal from a fuel quality sensor due to an inconsistent fuel supply.The following parameter is used only when the "Fuel Quality Input Type Configuration" is set to "Configured Value":
Fuel QualityA fixed LHV will be entered in the "Fuel Quality" parameter for engines that run on a consistent fuel supply.The ECM uses the LHV to help determine the fuel command to the fuel metering valve.The fuel command is sent to the fuel metering valve via the CAN data link.The following parameters are used only when the "Fuel Quality Input Type Configuration" is set to "4-20 mA":
Fuel Quality Sensor LHV Lower Setpoint
Fuel Quality Sensor LHV Upper SetpointThe ECM provides the following information to the fuel metering valve via the CAN data link:
"Fuel Specific Heat Ratio"
"Gas Specific Gravity"Note: For more details on these parameters, refer to Systems Operation/Testing and Adjusting, "Electronic Control System Parameters".Engine Load
The ECM must have values for the following parameters. The values are entered via the "Configuration" screen of Cat ET:
"Engine Load Input Configuration"
"Engine Output Power"
"Engine Driven Accessory Load Configuration"
"Generator Output Power Input Type Configuration" and data range
"Generator Efficiency"Note: For more details on these parameters, refer to Systems Operation/Testing and Adjusting, "Electronic Control System Parameters".Mode of Operation
The air/fuel ratio control has two basic modes of operation:
Open loop
NOX feedbackThe mode of operation is determined by the "Emissions Feedback Mode Configuration" parameter. Cat ET is used to change the mode of operation.Select "Feedback Disable" to activate the open loop mode.Select "NOx Feedback" to activate the feedback mode.Open Loop Mode
The open loop mode of operation uses no feedback.During operation in this mode, the ECM controls the air/fuel ratio with maps and with calculations for the desired air/fuel ratio.The