12602002 Mercury GROMMET

Table 1
Parameter Valid Range
Governor Gain Factor 0 to 40000
Governor Minimum Stability Factor 0 to 40000
Governor Maximum Stability Factor 0 to 40000 Note: No engineering units are associated with the "valid ranges" 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 set to 0, the system will revert to the factory default value.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 value for the governor gain factor is too large, the engine speed can overshoot the desired speed.
If the value for the governor gain factor is too small, the engine will accelerate slowly.Governor Minimum/Maximum Stability Factor
The governor minimum stability factor functions in order 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 in order 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 additional 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
Note: Record any adjustment to a governor setting. Write a brief summary about the engine response. Documenting each change to a parameter setting will allow you to attain the optimum engine response in the shortest amount of time.
Turn the Fuel Control Switch to the OFF 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.
Note: Ensure that the engine is running correctly before attempting any tuning of the governor. For example, there must not be any fault codes or derate events.
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: Any value may be returned to the factory default setting by entering 0 for the programmable parameter.
Set up a field performance test. For example, the engine has poor response during specific load changes.
Set the governor maximum stability factor to a level that is five times the governor minimum stability factor. The governor maximum stability factor helps when there is a sudden load increase or a decrease. For example, a change of engine speed that is 20 RPM greater than the setpoint. The governor maximum stability factor will not affect steady state stability. However, values for the governor maximum stability factor that are greater than seven times the governor minimum stability factor may cause oscillation during a load transient. The governor maximum stability factor can be raised above seven times the governor minimum stability factor. If the engine starts oscillating, the ratio of the governor maximum stability factor to the governor minimum stability factor must be lowered.
Whenever a gain adjustment is made, increase or decrease the governor gain factor, the governor minimum stability factor, and the governor maximum stability factor by the same percentage. A ten percent adjustment is considered a "fine" adjustment. There is no need to use steps that are smaller than ten percent. A 30 percent adjustment is large enough that a difference in engine response should be seen after the adjustment is made.
If the engine is oscillating or the engine is unstable with a constant load or with no load, lower the governor maximum stability factor in order to equal the governor minimum stability factor. This action should not affect engine response. If there is an effect on the engine response, the governor maximum stability factor is too high. After you determine that the governor maximum stability factor is not too high, set the governor maximum stability factor back to the previous value. Then, lower all three "Gains" by the same percentage.
If the change of the engine speed is too large during a load increase or a decrease in load, raise the governor maximum stability factor to seven times the governor minimum stability factor before adjusting the governor gain factor and the governor minimum stability factor. Note: The governor parameters in Cat ET are multipliers to the base governor maps that are stored in the software. The multipliers in Cat ET are active only when the engine is operating above 600 RPM. A change to the percentage value of a parameter in Cat ET applies an equivalent change to the percentage value of the base governor map at speeds above 600 RPM.Note: Usually, the "Governor Gain Factor" should be somewhat 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 the "Governor Gain Factor".