Electronic Control System Signature, ISX and QSX15 Engines – Engine Runs Rough or Misfires

Interview the operator to verify the complaint

Refer to Driveability-General Information, Driveability/Low Power Customer Complaint Form, and the Driveability Checklist at the end of Section TS. Follow the instructions on the forms before continuing with this tree.

Confirm if engine runs on after key-off by operating engine at high idle for one minute then shutting off engine

Refer to the Engine Will Not Shut Off symptom tree.

Condition occurs only at idle

Refer to the Engine Runs Rough at Idle symptom tree.

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 is operating at low ambient temperature

Check the winterfront, shutters, and under-the-hood air. Use under-the-hood intake air in cold weather. Refer to the Operation and Maintenance Manual, Bulletin 3666251.

Fuel grade is not correct for the application or the fuel quality is poor

Operate the engine from a tank of high-quality fuel. Refer to Fuel Recommendations and Specifications in the Operation and Maintenance Manual, Bulletin 3666251.

Electronic control module (ECM) calibration is malfunctioning

Verify the electronic control module (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 Internet Website or the INCAL™ calibration CD. 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 manual and Procedure 019-032.

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.

Fuel pump pulsation damper is cracked

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

Overhead adjustments are not correct

Measure and adjust the overhead settings. Refer to Procedure 003-004 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Fueling rail actuator or timing rail actuator is malfunctioning

Refer to Procedure 019-110 or Procedure 019-111.

Injector is malfunctioning

Perform the automated cylinder performance test. Replace injectors as necessary. Refer to Procedure 006-026 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.

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.

Engine brakes are malfunctioning

Check the engine brake operation, adjustment, and solenoid resistance. Repair or adjust as necessary. Refer to Procedure 020-004 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Camshaft timing is not correct

Refer to Procedure 001-088 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Cylinder head valve leak

Check the cylinder head for fuel leaks between the valves and valve seats. Refer to Procedure 002-004 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Vibration damper is damaged

Inspect the vibration damper. Refer to Procedure 001-052 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Internal engine damage

Analyze the oil and inspect the filters to locate an area of probable damage. Refer to Procedure 007-002 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.