3126B Petroleum Engine Caterpillar


Poor Acceleration or Response

Usage:

3126B Z2A

------ WARNING! ------

The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.

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Probable Causes

  • Active diagnostic codes or engine events

  • Incorrectly programmed parameters

  • Cold mode operation

  • Incorrect flash file

  • Incorrect throttle signal

  • Poor electrical connections

  • Turbocharger outlet pressure sensor, rated fuel position and/or FRC fuel position

  • Air inlet and exhaust system

  • Fuel supply

Recommended Actions

Active Diagnostic Codes or Engine Events

Certain diagnostic codes and/or event codes may cause poor performance. Connect the Caterpillar Electronic Technician (ET) and check for active codes and for logged codes. Troubleshoot any active codes that are present before continuing with this procedure.

Incorrectly Programmed Parameters

Determine the type of throttle that is used in the application. Program the parameters to match the type of throttle that is used. Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" for troubleshooting information.

Note: If the parameters are not programmed correctly, then the engine will have poor performance.

Cold Mode Operation

The Electronic Control Module (ECM) will activate the cold start strategy during engine warm-up in cold weather.

When the cold start strategy is activated, the engine's power will be limited.

Incorrect Flash File

Verify that the correct flash file is installed.

Incorrect Throttle Signal

Use Cat ET to view the status for the throttle position on the status screen. Operate the throttle from the low idle position to the high idle position. The status should be 0 percent at low idle and the status should be 100 percent at high idle. If the status cannot operate in the full range, refer to the calibration procedure Troubleshooting, "Throttle Position Sensor - Calibrate".

Diagnostic codes that are related to the J1939 data link will prevent correct operation of the throttle if the throttle position is transmitted over the data link. If there is a problem with the data link, the engine will remain at low idle until the data link is repaired.

Poor Electrical Connections

Check for the correct installation of the J2/P2 and J1/P1 ECM connectors. Check the J300/P300 valve cover connector. Refer to Troubleshooting, "Electrical Connectors - Inspect".

Turbocharger Outlet Pressure Sensor, Rated Fuel Position and/or FRC Fuel Position

  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"
    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.

  1. Monitor the status of "Boost Pressure" and "Atmospheric Pressure" for normal operation on Cat ET. When the engine is not running, "Boost Pressure" should be 0 kPa (0 psi).

    Note: A problem with the FRC will only cause black smoke during acceleration. A problem with the FRC will not cause black smoke during steady state operation.

Air Inlet and Exhaust System

  1. Check for an air filter restriction. If necessary, service the air filter element.

  1. Check for the correct operation of the turbocharger. Refer to Systems Operation/Testing and Adjusting for information that is related to testing the turbocharger.

  1. Check for air inlet restrictions and/or leaks. Check for exhaust restrictions. Refer to Systems Operation/Testing and Adjusting, "Air Inlet and Exhaust System - Inspect" for more information.

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 debris which may block the fuel supply.

  1. Check for air in the low pressure fuel supply circuit. Refer to Systems Operation/Testing and Adjusting, "Air In Fuel - Test". If air is present in the low pressure fuel supply circuit, prime the fuel system. Refer to Operation and Maintenance Manual, "Fuel System - Prime".

  1. Check the fuel pressure. Refer to Systems Operation/Testing and Adjusting, "Fuel System Pressure - Test".

  1. Check fuel quality. In temperatures below 0 °C (32 °F), check for solidified fuel (wax). Refer to the Operation and Maintenance Manual for cold weather operation.

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