C-10, C-12, C-15 and C-16 Industrial Engines – Poor Acceleration or Response

Probable Causes

  • Diagnostic codes

  • Event codes

  • Cold mode

  • Flash file

  • Throttle signal

  • Electrical connectors

  • Unit injectors

  • Intake manifold (boost) pressure sensor

  • Air inlet and exhaust system

  • 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, Event Codes and Derates

Certain diagnostic codes, event codes and/or derates may cause poor performance. Connect the 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.

Cold Mode

Use Cat ET to verify that the engine has exited cold mode. Cold mode operation may slow throttle response.

Flash File

Verify that the correct flash file is installed.

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 the diagnostic functional test Troubleshooting, “Electrical Connectors – Inspect”.

Unit Injectors

  1. Perform the “Injector Solenoid Test” on Cat ET in order to determine if all of the injector solenoids are being energized by the ECM.
  1. Perform the “Cylinder Cutout Test” on Cat ET in order to identify any injectors that might be misfiring. Refer to the diagnostic functional test Troubleshooting, “Injector Solenoid Circuit – Test”.

Intake Manifold (Boost) Pressure Sensor

  1. 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.

    Table 1
    “Fuel Position” = “Rated Fuel Limit”    
    “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.

  1. Monitor the status of “Boost Pressure” and of “Atmospheric Pressure” for normal operation on Cat ET. When the engine is not running, the correct value for “Boost Pressure” is 0 kPa (0 psi).

Air Inlet and Exhaust System

  1. Observe the check engine lamp. Check for an air filter restriction indicator. Clean plugged air filters or replace plugged air filters. Refer to the Operation and Maintenance Manual.
  1. Check the air inlet and exhaust system for restrictions and/or leaks. Refer to Systems Operation/Testing and Adjusting, “Air Inlet and Exhaust System”.

Fuel Supply

  1. 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.
  1. Check the fuel tank for foreign objects which may block the fuel supply.
  1. 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”.

  1. 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.


    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.

  1. Check the fuel pressure after the fuel filter while the engine is being cranked. Refer to Systems Operation/Testing and Adjusting, “Fuel System” 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.