Engine Runs Rough or Misfires

Symptom Tree  t062

This is symptom tree t062
Cause Correction

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF for fault code troubleshooting.

 

Condition occurs only at idle

Refer to the Engine Runs Rough at Idle symptom tree.

 

White smoke is present

Refer to the Smoke, White – Excessive symptom tree.

 

Black smoke is present

Refer to the Smoke, Black – Excessive symptom tree.

 

Engine is operating at low ambient temperature

Check the shutters and engine compartment air. Refer to Cold Weather Operation, Bulletin 3387226, and the operation and maintenance manual. Use intake air from under the hood.

 

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 the Fuel Recommendations and Specifications in the Operation and Maintenance Manual N14 Plus Series Engines, Bulletin 3666136 or the Operation and Maintenance Manual M11 Plus Series Engines, Bulletin 3666143.

 

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 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 in the fuel system

Check for air in the fuel system. Refer to Procedure 006-003 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Fuel inlet restriction

Check for fuel inlet restriction. Refer to Procedure 006-020 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Engine position sensor (EPS) or circuit is malfunctioning or wiring is not correct

Check the engine position sensor or circuit. Refer to Procedure 019-038 or 019-039.

 

Fuel pump is malfunctioning

Check the fuel pump output pressure, pulsation damper, and pressure regulator. Replace the fuel pump if necessary. Refer to Procedures 005-011, 005-016, and 005-031 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Alternator is malfunctioning

Temporarily disconnect the alternator and run the engine. Replace the alternator if necessary. Refer to the OEM service manual.

 

Vehicle ground circuit has an intermittent open circuit

Check the ground circuit for loose or broken connections. The battery cable grounds must measure within OEM specifications for voltage drop under electrical load. Refer to Procedure 019-008.

 

Injector is malfunctioning

Perform the automated cylinder performance test. Replace injectors as necessary. Refer to Procedure 006-026 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Engine brake adjustment is not correct

Adjust the engine brakes. Refer to Procedure 020-001 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Overhead adjustments are not correct

Measure and adjust the overhead settings. Refer to Procedure 003-004 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

Static injection timing is not correct

Check the static injection timing. Refer to Procedure 006-025 in the Troubleshooting and Repair Manual N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

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 N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 

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 N14 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666142, or the Troubleshooting and Repair Manual M11 Series Engines (STC, CELECT™, CELECT™ Plus Models), Bulletin 3666139.

 
Last Modified:  16-Jan-2004

Leave a Reply

Your email address will not be published. Required fields are marked *