C7 and C9 Industrial Engines Troubleshooting – Acceleration Is Poor or Throttle Response Is Poor

A. Connect Cat® Electronic Technician (ET) to the service tool connector.

Repair: Troubleshoot the code.

Result: A diagnostic code is not present.
Proceed to Test Step 2.

A. Use Cat ET to verify that the correct parameters are being used. Refer to Troubleshooting, “Configuration Parameters” for additional information.

Proceed to Test Step 3.

Result: The parameters are not correct.

Repair: Input the correct parameters. Refer to Troubleshooting, “Configuration Parameters” for additional information.

A. 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.

Result: The throttle signal is not stable.

Repair: Make the necessary repairs, Refer to the appropriate circuit test.

A. Observe the check engine lamp. Check for an air filter restriction indicator. Replace any plugged air filters. Refer to the Operation and Maintenance Manual.

B. Check the air inlet and exhaust system for restrictions and/or leaks.

Proceed to Test Step 5.

Result: There are restrictions in the air inlet or exhaust system.

Repair: Make the necessary repairs, Refer to Systems Operation/Testing and Adjusting, “Air Inlet and Exhaust System – Inspect” for additional information.

Refer to Systems Operation/Testing and Adjusting, “Fuel System” for additional information.

A. Visually check the fuel level in the fuel tank. Do not rely on the fuel gauge only.

B. Ensure that the vent in the fuel cap is not filled with debris.

C. Ensure that the fuel supply valve (if equipped) is in the full OPEN position.

D. Inspect the fuel system. Refer to Systems Operation/Testing and Adjusting, “Fuel System – Inspect” for additional information.

E. Cold weather adversely affects the characteristics of the fuel. Refer to the engines Operation and Maintenance Manual for information on improving the characteristics of the fuel during cold-weather operation. Cold mode (if applicable) is activated whenever the engine coolant temperature falls below a predetermined value. Monitor the status screen on Cat ET in order to verify that the engine has exited cold mode. Observe the reading for coolant temperature on the Cat ET.

Refer to “Cold Mode Operation” within the Systems Operation, “General Information”.

F. Check fuel quality. Refer to Systems Operation/Testing and Adjusting, “Fuel Quality – Test” for the proper procedure. Check the fuel tank for debris or foreign objects which may block the fuel supply.

G. Check for the proper operation of the fuel transfer pump. Refer to Systems Operation/Testing and Adjusting, “Fuel System” for test information.

Proceed to Test Step 6.

Result: The fuel pressure is not OK.

Repair: Replace the fuel filters. Clean the primary filter/water separator of debris. Refer to the Operation and Maintenance Manual for details.

A. Check accessories and parasitic loads on the engine.

Proceed to Test Step 7.

Result: There is a parasitic load.

Repair: Remove the parasitic load.

A. Check the valve lash. The valve lash can affect the performance of the engine.

Repair: Set the valve lash. Refer to Testing and Adjusting, “Engine Valve Lash – Inspect/Adjust” for the correct procedure.
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