0125432 JOHNSON BULB

The correct air/fuel ratio also helps ensure stable operation. To adjust the air/fuel ratio, perform the following procedure.
Connect a properly calibrated emissions analyzer to the exhaust stack.
Connect the Cat® Electronic Technician (Cat ET) to the service tool connector.
Verify that the configuration parameters for the "Fuel Quality" and the "Gas Specific Gravity" are programmed correctly. Use the values that are obtained from the Caterpillar Software, LERW4485, "Gas Engine Rating Pro (GERP)".Note: Use of only the data from the gas analysis can result in incorrect settings.
Verify that the value for the "Fuel Specific Heat Ratio" parameter is correct. Enter a value of 1.4 for processed, dry pipeline natural gas.
Set the "Desired Engine Exhaust NOx Level Setting" parameter to a value of "80" to "180".
Start the engine. Increase the engine speed to high idle rpm. Verify that the engine is stable.If the engine is unstable, perform the following procedure.
Record the values for these parameters:
"Governor (Proportional) Gain Percentage"
"Governor (Integral) Stability Percentage"
Set the values for the "Governor (Proportional) Gain Percentage" and "Governor (Integral) Stability Percentage" parameters to 100%.
Adjust the "Fuel Quality" parameter until the engine becomes stable and the exhaust oxygen is approximately four percent. Verify that the exhaust port temperatures are below the setpoint for a warning.
Adjust the primary governor. Refer to Systems Operation/Testing and Adjusting, "Engine Governing - Adjust".
Close the main circuit breaker for the generator to engage the generator.Note: When the engine load becomes greater than 40 percent, the air/fuel ratio control will operate in the feedback mode.
Slowly ramp the load up to 30 percent.Note: When the air/fuel ratio control is in the feedback mode, the Fuel Correction Factor (FCF) may no longer be 100 percent. The Electronic Control Module may adjust the FCF to compensate for the fuel quality and for the ambient conditions.
Verify that the reading on Cat ET for the power output of the generator agrees with the reading indicated by the switchgear.If the readings do not agree, adjust the "Generator Output Power Sensor Scale Factor" and/or the "Generator Output Power Sensor Offset" parameters. Also, make sure that the "Engine Output Power Configuration" and the "Engine Driven Accessory Load Configuration" parameters are accurately programmed. Refer to Systems Operation/Testing and Adjusting, "Electronic Control System Parameters".
Slowly ramp up to 70 percent load. Verify that the engine is stable.If the engine is unstable, adjust the auxiliary governor. Refer to Systems Operation/Testing and Adjusting, "Engine Governing - Adjust".
Compare the exhaust reading from the emissions analyzer to the NOx emission parameter in Cat ET. If the two parameters are further than 10ppm, the NOx sensor on the engine needs a calibration performed. Refer to Troubleshooting, M0074324, "Nitrogen Oxide Sensor - Calibrate" for additional information.
Slowly ramp up to 100 percent load or the maximum load capability per the performance data for the given site conditions or customer site requirements, whichever is lower.
Verify that the reading on Cat ET for the power output of the generator agrees with the reading indicated by the switchgear.
Compare the exhaust reading from the emissions analyzer to the NOx emission parameter in Cat ET. If the two parameters are further than 10ppm, the NOx sensor on the engine needs a calibration performed. Refer to Troubleshooting, M0074324, "Nitrogen Oxide Sensor - Calibrate" for additional information.
Adjust the "Desired Engine Exhaust NOx Level Setting" parameter to obtain the values of emissions that are required at the site.Use the emissions analyzer to verify that the values of emissions meet the requirements of the site.