0327769 JOHNSON ORIFICE PLUG, (No. 70D)

Table 1
Parameter Default Value Valid Range
Governor Gain Factor 100% 0.1% - 1,000%
Governor Minimum Stability Factor 100% 0.1% - 1,000%
Governor Maximum Stability Factor 100% 0.1% - 1,000% Note: No engineering units are associated with the numbers in table 1.Note: The range of the programmable setting is wide for flexibility. Do not expect to use the whole range. If the programmable setting is greater than the valid range, the system will revert to the factory default value.Do not perform this procedure until you read this information and you understand this information.Gain Explanations
Governor Gain Factor
The "Governor Gain Factor" is multiplied by the engine speed error. This value is derived by calculating the difference between the desired speed and the actual speed.
If the "Governor Gain Factor" value is too large, the engine speed can overshoot the desired speed.
If the "Governor Gain Factor" value is too small, the engine will accelerate slowly.Governor Minimum/Maximum Stability Factor
The "Governor Minimum Stability Factor" functions to eliminate steady state speed error. The "Governor Minimum Stability Factor" is used by the Electronic Control Module (ECM) when the steady state speed error is less than 20 rpm.The "Governor Maximum Stability Factor" functions to eliminate steady state speed error. The "Governor Maximum Stability Factor" is used by the ECM when the steady state speed error is increasing and the engine speed error is greater than 20 rpm.
If the "Governor Minimum Stability Factor" or the "Governor Maximum Stability Factor" is set too high, the ECM will provide more fuel. The additional fuel will cause the engine speed to overshoot. The additional fuel will also cause the engine speed to oscillate.
If the "Governor Minimum Stability Factor" or the "Governor Maximum Stability Factor" is set too low, the engine will not achieve a steady state operation quickly.Tuning Procedure
Turn the Engine Control Switch (ECS) to the COOLDOWN/STOP position. Connect the Caterpillar Electronic Technician (ET). Enable the engine overspeed protection prior to the adjustment procedure. Adjusting governor gain parameters without engine overspeed protection can result in serious engine damage. Ensure that engine overspeed protection is ON. Engine overspeed is configured on the setup screen of "Service Monitoring System" in Cat ET.
Personal injury or death can result from engine overspeed.If the engine overspeeds, it can cause injury or parts damage. The engine should be equipped with a separate shutdown device, to protect against engine overspeed. Do not use for emergency shutdown.
Start the engine. Observe the control panel to ensure that the engine has reached the rated speed. The control panel will serve as the reference point for engine speed during this procedure.
Go to the configuration parameters screen in Cat ET.Note: A factory password is required for adjustment of the governor gain parameters. Once the password is entered, the values for the governor gain parameters can be adjusted. If a parameter value that is not a governor gain parameter is altered, a new password will be required. If the configuration parameters screen is stopped during the adjustment of a governor gain parameter, a new factory password will be required.Note: Any value may be returned to the factory default setting by typing a number that is greater than the valid range. For example, typing 40,000 will reset a value to the factory default.
Set up a field performance test. For example, the engine has poor response during specific load changes.
Perform the desired load change from step 4. Observe the response of the engine by viewing the engine speed on the control panel. Observe the engine response by looking at the frequency meter or by listening to the response of the engine.
Determine the setting to adjust. Refer to "Gain Explanations" and "Governor Minimum/Maximum Stability Factor".Note: Usually, the "Governor Gain Factor" should be lower than the "Governor Minimum Stability Factor" for optimum performance. The "Governor Maximum Stability Factor" is typically a smaller value than the "Governor Minimum Stability Factor" and "Governor Gain Factor".
Repeat steps 5,6, and 7 until a desired engine response can be met. Use large adjustments (ten percent of original gain) initially for a coarse adjustment to engine response. Use smaller adjustments (one percent of total gain) as the engine response is closer to the desired response.