Probable Causes
- Diagnostic codes
- Event codes
- Cold mode
- Throttle signal
- Electrical connectors
- Unit injectors
- Injection actuation pressure
- Intake manifold (boost) pressure sensor
- Air inlet and exhaust system
- Parameters
- Fuel supply
Recommended Actions
Note: If the problem only occurs under certain conditions, test the engine under those conditions. Examples of certain conditions are high engine speed, full load and engine operating temperature. Troubleshooting the symptoms under other conditions can give misleading results.
Diagnostic Codes and Event Codes
Certain diagnostic codes and/or event codes may cause poor performance. Connect Caterpillar Electronic Technician (ET) and check for active codes and/or for logged codes. Troubleshoot any codes that are present before continuing with this procedure.
Note: An active derate will limit engine power. If a derate is active, the "Engine Derate" will appear on any status screen on the Caterpillar Electronic Technician (ET). Determine the cause for the derate and correct the conditions that cause the derate. Verify that the set points for "Derate" that are in the programmable monitoring system have been programmed to the correct values.
Cold Mode
- Use Cat ET to verify that the engine has exited cold mode. Cold mode operation may cause the engine to run rough and engine power may be limited.
- Ensure that the air inlet heater is operating correctly. For additional information on the air inlet heater, refer to Troubleshooting, "Air Inlet Heater Circuit - Test".
Throttle Signal
Monitor the status for "Throttle Position" on Cat ET. Verify that the status for "Throttle Position" is stable and that the engine is able to reach high idle speed. Refer to the appropriate diagnostic test for your application:
- Troubleshooting, "Throttle Position Sensor Circuit - Test"
- Troubleshooting, "Throttle Switch Circuit - Test"
- Troubleshooting, "Speed Control - Test"
Electrical Connectors
Check for correct installation of the J1/P1 and J2/P2 Electronic Control Module (ECM) connectors and the unit injector connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect".
Unit Injectors
- Perform the "Injector Solenoid Test" on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
- Perform the "Cylinder Cutout Test" on Cat ET in order to identify any misfiring cylinder(s). Refer to Troubleshooting, "Injector Solenoids Circuit - Test".
Injection Actuation Pressure
- Check the engine oil level. Engine oil supplies the injection actuation pressure circuit. The engine oil must be kept at the proper level.
- If service has recently been performed on the engine, air may be present in the injection actuation pressure circuit. Allow the engine to fully warm up and operate the engine under load in order to ensure that the air has been purged from the injection actuation pressure circuit.
- Compare the actual actuation pressure and the desired actuation pressure on Cat ET. If these readings do not agree within 2000 kPa (290 psi), refer to Troubleshooting, "Injection Actuation Pressure Sensor - Test".
Intake Manifold (Boost) Pressure Sensor
- Monitor the status of "Fuel Position", "Rated Fuel Limit", and "FRC Fuel Limit" on Cat ET while the engine is operating under full load. These parameters should reflect the information below.
Show/hide table
Table 1 "Fuel Position" = "Rated Fuel Limit" and "Fuel Position" < "FRC Fuel Limit" If "Fuel Position" equals "Rated Fuel Limit" and "Fuel Position" is less than "FRC Fuel Limit", the electronics are operating correctly. Otherwise, proceed with the next Step.
- Verify that there are no active diagnostic codes.
- Monitor the status of "Intake Manifold (Boost) Pressure" and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, the correct value for "Intake Manifold (Boost) Pressure" is 0 kPa (0 psi).
Air Inlet and Exhaust System
- Observe the indicator lamps. Check for an air filter restriction indicator. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.
- Check the air inlet and exhaust system for restrictions and/or for leaks. Refer to Systems Operation/Testing and Adjusting.
Parameters
Check the following parameters on Cat ET:
- Verify that the injector codes are programmed.
- "Throttle position sensor"
- "Desired speed input configuration"
Determine the type of throttle that is used in the application. Program the parameters to match the type of throttle that is used.
Note: If the parameters are not programmed correctly, then the engine will have poor performance.
Fuel Supply
- Check the fuel lines for the following problems: restrictions, collapsed lines and pinched lines. If problems are found with the fuel lines, repair the lines and/or replace the lines.
- Check the fuel tank for foreign objects which may block the fuel supply.
- Prime the fuel system if any of the following procedures have been performed:
- Replacement of the fuel filters
- Service on the low pressure fuel supply circuit
- Replacement of unit injectors
Note: A sight glass in the low pressure supply line is helpful in diagnosing air in the fuel. Refer to Systems Operation/Testing and Adjusting, "Air in Fuel - Test".
- Replacement of the fuel filters
| NOTICE |
|---|
Do not crank the engine continuously for more than 30 seconds. Allow the starting motor to cool for two minutes before cranking the engine again. |
- 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 pressure after the fuel filter while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting for the correct pressure values. If the fuel pressure is low, replace the fuel filters. If the fuel pressure is still low, check the following items: fuel transfer pump, fuel transfer pump coupling and fuel pressure regulating valve. Refer to Systems Operation/Testing and Adjusting.