0390563 JOHNSON MOTOR COVER ASSY., Johnson 50 models

ECM Identification Parameters
Equipment ID
The customer can assign an "Equipment ID" for identification for the engine application.Engine Serial Number
The engine serial number is programmed into the ECM at the factory. The number is stamped on the engine information plate.Timing Control
These timing parameters allow the customer to program ignition timing electronically in order to meet the needs for specific applications and installations.Note: The actual ignition timing at a given instance may vary from the desired timing value. This variance is due to variations in the engine speed, engine load, or detonation.First Desired Timing
The "First Desired Timing" is determined with the methane number of the primary fuel that is used. Use the Engine Performance Sheet, "Fuel Usage Guide". The ECM selects the "First Desired Timing" when the timing select switch creates an open circuit for terminal J1-20 at the master ECM.
Note: The desired timing should be determined by using the Caterpillar Software, LEKQ6378, "Methane Number Program" with the results that are from the fuel analysis. Use of only the data from the gas analysis can result in incorrect settings.Second Desired Timing
The "Second Desired Timing" is determined with the methane number of the alternate fuel that is used and the Engine Performance Sheet, "Fuel Usage Guide". The ECM selects the "Second Desired Timing" when the timing select switch creates a short circuit to ground for terminal J1-20 at the master ECM.If an alternate fuel is not used, enter the same timing value for the "Second Desired Timing" parameter that is entered in the "First Desired Timing" parameter.Desired Engine Timing Offset
This feature provides the offset of engine ignition timing to compensate for timing errors due to resistances in electrical circuitry and stackup of mechanical tolerances.This parameter provides a manual method that will allow additional timing adjustment to be performed after calibration of the speed/timing sensor. Perform a negative adjustment to this parameter for retardation of engine timing. Perform a positive adjustment to this parameter in order to advance the engine timing. Only perform an adjustment to this parameter if engine operating indicators and measured data indicate that an adjustment is required.Air/Fuel Ratio Control
Before the initial start-up, a current gas analysis is required. Periodic gas analyses are also recommended. Use the Caterpillar Software, LEKQ6378, "Methane Number Program" in order to calculate the parameters for air/fuel ratio control for Caterpillar Gas Engines. The results are programmed into the ECM.Note: Use the Caterpillar Software, LEKQ6378, "Methane Number Program". The improper programming of the air/fuel ratio control can result in damage to the engine.The Caterpillar Software, LEKQ6378, "Methane Number Program" is also contained in Caterpillar Software, LERW4485, "GAS ENGINE RATING PRO - VERSION 3.01". This software also contains information that is related to engine performance.Fuel Quality
This parameter is the fuel Low Heat Value (LHV). The air/fuel ratio control of the ECM will compensate for some inaccuracy in this setting. The ECM derives a corrected value that is multiplied by the "Fuel Correction Factor". The status of the parameter can be viewed with Cat ET.The "Fuel Quality" parameter can be used to change the air/fuel ratio when the engine is operating in the open loop mode. To richen the air/fuel mixture, reduce the value. The calculation will compensate for the reduced LHV by increasing the fuel flow. To lean the air/fuel mixture, increase the value. The calculation will compensate for the increased LHV by reducing the fuel flow.Gas Specific Gravity
This parameter is the fuel-specific gravity in relation to the specific gravity of air. The ECM does not use this information. The ECM provides the information to the fuel metering valve via the CAN data link. Some fuel metering valves require an input for the "Gas Specific Gravity" in order to precisely meter the fuel flow.Fuel Specific Heat Ratio
This parameter is a ratio of the fuel-specific heat at a constant pressure and at a constant volume. The ratio is also known as "k". The ratio is related to the expansion of the gas across the fuel metering valve. The ECM does not use this information. The ECM provides the information to the fuel metering valve via the CAN data link. Some fuel metering valves require an input for the "Fuel Specific Heat Ratio" in order to precisely meter the fuel flow.Emissions Feedback Mode configuration
The "Emissions Feedback Mode configuration" can be set to "NOx Feedback" or to "Feedback Disabled". This feature allows the feedback mode to be disabled in order to troubleshoot the engine. The disabling of this feature can help determine whether the air/fuel ratio control is the cause of instability of the engine.If the signal from the NOX sensor is not available, the control system does not have information necessary for maintaining the desired exhaust emissions.If there is a problem with the NOX sensor, this parameter can be set to "Feedback Disabled". "Feedback Disabled" allows the engine to run in the open loop mode until a new sensor is obtained. During operation in this mode, an emissions analyzer must be used to verify the emissions level. The "Fuel Quality" parameter is adjusted in order to change the air/fuel mixture for the engine.When the "Emissions Feedback Mode configuration" is set to "NOx Feedback", adjustment of the "Fuel Quality" parameter does not affect the air/fuel ratio. Do not adjust the "Fuel Quality" parameter when the "Emissions Feedback Mode configuration" is set to "NOx Feedback".Note: Do not operate an engine that is unattended in the open loop mode if the fuel has an LHV that is changing. The engine risks a shutdown due to lean misfire or to detonation.Desired Engine Exhaust NOx Level Setting
The ECM contains a control map for the NOX emissions that is programmed at the factory. The "Desired Engine Exhaust NOx Level Setting" parameter is used to trim this control map when the engine is in "NOx Feedback" mode. If the measured NOX emissions are not the required value, decrease the "Desired Engine Exhaust NOx Level Setting". The parameter decrease is to lean the fuel mixture. Increase the "Desired Engine Exhaust NOx Level Setting" parameter in order to