Electronic Control System Signature, ISX and QSX15 Engines – Engine Speed Surges Under Load or in Operating Range

Electronic fault codes active or high counts of inactive fault codes

Read the fault codes with an electronic service tool. Refer to Section TF for fault code troubleshooting.

Engine speed also surges at idle

Refer to the Engine Speed Surges at Low or High Idle symptom tree.

Accelerator pedal position sensor or circuit is malfunctioning

Check for accelerator pedal or lever restriction. Check the percent throttle reading on an electronic service tool. Check the accelerator pedal position sensor and the circuit. Refer to Procedure 019-085 and 019-086.

Air in the fuel system

Check for air in the fuel system. Refer to Procedure 006-003 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Fuel inlet restriction

Check for fuel inlet restriction. Refer to Procedure 006-020 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Fuel drain line restriction

Check the fuel drain lines for restriction. Refer to Procedure 006-012 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Electronic control module (ECM) calibration is malfunctioning

Verify the ECM calibration is correct. Check the calibration revision history for applicable fixes to the calibration stored in the ECM. Refer to the calibration history spreadsheet Click here to see ecm_calibration_rev_history.xls

on QuickServe® Online or the INCAL™ CD-ROM. Compare the calibration stored in the ECM with the engine rating and the Control Parts List (CPL), Bulletin 4021326 or 4021327. If necessary, recalibrate the ECM. Refer to the appropriate electronic service tool manual and Procedure 019-032.

Air intake system restriction is above specification

Check the air intake system for restriction. Clean or replace the air filter and inlet piping as necessary. Refer to Procedure 010-031 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Exhaust system restriction is not within specification

Check the exhaust system for restrictions. Refer to Procedure 011-009 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Turbocharger wastegate is malfunctioning (if equipped)

Check the wastegate for correct operation. Refer to Procedure 010-050 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Injector malfunctioning

Perform the Injector Check Valve Leak Test. Repair or replace the injectors as necessary. Refer to Procedure 006-026 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Fuel pump is malfunctioning

Check the fuel pump output pressure, pulsation damper, and pressure regulator. Replace the fuel pump if necessary. Refer to Procedure 005-016 and 005-031 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Vehicle speed sensor (VSS) or circuit is malfunctioning

Check the vehicle speed sensor and circuit. Refer to Procedure 019-090 and 019-091.

Engine position sensor (EPS) or circuit is malfunctioning

Check the engine position sensor and circuit. Refer to Procedure 019-038.

Engine brake adjustment is not correct

Adjust the engine brakes. Refer to Procedure 020-004 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Moisture in the wiring harness connectors

Dry the connectors with Cummins electronic cleaner, Part Number 3824510.