- Excessive load
- Dirty air filter
- Torque limiting feature
- Problem with the vehicle's brakes
- Programmable parameters
- Air inlet system
- Fuel quality
- Primary fuel filter
- Fuel system
- Problem with a cylinder
Verify that the load is not excessive for the engine's rating.
Inspect the air filter. Replace the air filter if the air filter is dirty.
Check the Torque Limiting Feature
Verify that the "Torque Limit" configuration parameter is programmed correctly for the application.
Verify that the torque limit switch is Off.
Cat ET does not indicate the status of the torque limit switch. If the torque limit switch is Off and you suspect that the ECM is limiting the engine's power, check the circuit for the torque limit switch. Refer to Troubleshooting, "Power Take-Off - Test".
Verify that the vehicle's brakes are working correctly.
Check the Programmable Parameters
Use the Caterpillar Electronic Technician (ET) to check the status of the following parameters:
- "Top Engine Limit"
- "Vehicle Speed Limit"
- "Lower Gears Engine RPM Limit"
- "Intermediate Gears Engine RPM Limit"
- "Gear Down Protection Engine RPM Limit"
Verify that the value for each parameter is correct for the vehicle.
Check the air inlet system for restrictions and/or leaks. Refer to the Testing And Adjusting manual for the correct procedure.
Cold weather adversely affects the characteristics of the fuel. Refer to the Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold weather operation.
Check the fuel quality. Refer to the Testing And Adjusting manual for the correct procedure.
Check the Rating of the Primary Fuel Filter
An improperly sized primary fuel filter reduces engine performance by restricting fuel flow to the engine. The primary fuel filter must be able to provide a minimum flow rate at the required micron size in order to deliver an adequate amount of fuel at the required fuel cleanliness. The filter must meet both of the following requirements:
Flow Rate in Gallons Per Hour - The flow rate of the primary fuel filter must be at least 95 gallons per hour.
Micron Size - The micron rating of the primary fuel filter must be 10 microns or less.
Refer to Troubleshooting, "Fuel System Pressure - Test" for the correct procedure.
Perform a PAR Dyno Test or a Vehicle Road Test
Perform a PAR dyno test or a vehicle road test.
Use the following procedure if you perform a vehicle road test:
Monitor the fuel position, the rated fuel limit, and the FRC limit. While the vehicle is operating under full load, the parameters should meet the following conditions:
- The fuel position is equal to the rated fuel limit.
- The fuel position is less than the FRC limit.
If the fuel position is equal to the rated fuel limit and the fuel position is less than the FRC limit, the electronic control system is operating correctly.
If the fuel position is not equal to the rated fuel limit and/or the fuel position is not less than the FRC limit, check the intake manifold pressure on Cat ET when the engine is not running. The intake manifold pressure should be 0 kPa (0 psi).