C2.4 Tier 4 Final Engines for Caterpillar Built Machines Caterpillar

Acceleration Is Poor or Throttle Response Is Poor

Usage:

Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.

Probable Causes

Codes
Throttle Signal
Air Inlet and Exhaust System
Fuel System
Engine Load
Valve Lash

Recommended Actions

Note: The procedures have been listed in order of probability. Complete the procedures in order.

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.

Show/hide table

Table 1
Troubleshooting Test Steps	Values	Results
1. Engine Derate or Active Codes A. Certain diagnostic codes and/or event codes may cause poor performance. B. If no diagnostic codes are present, then the engine is operating normally. The following list contains conditions that can cause derates: 1. Elevated altitude 2. Elevated inlet air temperature 3. Elevated ambient temperature	Engine Derate or Active Codes	Result: A diagnostic code is present. Troubleshoot the code. Result: A diagnostic code is not present. Proceed to Test Step 2.
2. Check the Fuel System 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. Inspect the fuel system for external leaks. D. Check that there is no air in the clear primary fuel filter. Refer to Testing and Adjusting, Low Fuel Pressure System-Test. E. Change the primary fuel filter and the in-line filter for the fuel transfer pump. 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. Replace the pre-filter if excessive contamination or if the maintenance interval is exceeded. Refer to Testing and Adjusting, Low Fuel Pressure System-Test for test information.	Fuel system	Result: The fuel system is OK. Proceed to Test Step 3. Result: The fuel system is not OK. Make the necessary repairs.
3. Throttle Signal 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. NOTE: The desired engine speed will not show an rpm greater than the rated engine speed of 2400 rpm (305.5E2), 2200 rpm (307E2, 305E2, 304.5E2, 304E2,903C2, and 902C2).	Throttle Signal	Result: The throttle signal is stable. Proceed to Test Step 4. Result: The throttle signal is not stable. Make the necessary repairs, Refer to the appropriate circuit test.
4. Restriction in the Air Inlet and Exhaust System 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.	Restrictions	Result: There are no restrictions in the air inlet or exhaust system. Proceed to Test Step 5. Result: There are restrictions in the air inlet or exhaust system. Make the necessary repairs, Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System - Inspect" for additional information.
5. Engine Load A. Check accessories and parasitic loads on the engine.	Engine loads	Result: There is not a parasitic load. Proceed to Test Step 6. Result: There is a parasitic load. Remove the parasitic load.
6. Valve Lash A. Check the valve lash. The valve lash can affect the performance of the engine.	Valve lash	Result: The valve lash is not set correctly. Set the valve lash. Refer to Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust" for the correct procedure. STOP

Complete the procedure in the order in which the steps are listed.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).