M11 Series – Service Manual – Engine Runs Rough at Idle

Idle characteristics of CELECT™ and CELECT™ Plus systems are different than characteristics of the PT® system

Normal performance. No corrections are necessary.

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Troubleshooting and Repair Manual for CELECT™ Plus Systems, Bulletin 3666130, or Section TF in the Troubleshooting and Repair Manaul for CELECT™ Systems, Bulletin 3666084 for fault code troubleshooting..

Coolant temperature sensor is malfunctioning

Use an electronic service tool to check the coolant temperature sensor circuit. Refer to Procedure 019-019 in the Troubleshooting and Repair Manual for CELECT™ Plus Systems, Bulletin 3666130, or in the Troubleshooting and Repair Manual for CELECT™ Systems, Bulletin 3666084.

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 tool manual and Procedure 019-032 in the Troubleshooting and Repair Manual for CELECT™ Plus Systems, Bulletin 3666130, or in the Troubleshooting and Repair Manual for CELECT™ Systems, Bulletin 3666084.

Engine idle speed is set too low (mechanical fuel systems)

Adjust the fuel pump idle speed. Refer to Procedure 005-029.

Engine idle speed is set too low (electronically controlled fuel systems)

Verify the correct idle speed setting. Increase the idle speed with the idle increment switch or an electronic service tool.

Engine is operating above recommended altitude (STC engines only)

Derate the engine by 4 percent for every 300 meters [1000 feet] of altitude above 3600 meters [12,000 ft]. Refer to the Engine Data Sheet.

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 Operation of Diesel Engines in Cold Climates, Bulletin 3379009.

Fuel supply pressure is below specification

Measure the fuel supply pressure. Refer to Procedure 005-011.

Fuel pump pulsation damper is cracked

Inspect the fuel pump pulsation damper. Replace the pulsation damper if necessary. Refer to Procedure 005-031.

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 for Cummins Engines, Bulletin 3379001 and the OEM service manual.

White smoke is present

Check the STC plumbing to each cylinder for restriction or loss of flow. Refer to Procedures 006-045 and 006-046.

Engine mounts are worn, damaged, or not correct

Check the engine mounts. Refer to the OEM service manual.

Overhead adjustments are not correct

Adjust the overhead settings. Refer to Procedure 003-004.

Injector is malfunctioning (CELECT™ and CELECT™ Plus)

Perform the automated cylinder performance test. Replace injectors as necessary. Refer to Procedures 006-005 and 006-026.

Injector is malfunctioning (PT/STC)

Remove and check the injectors. Replace injectors as necessary. Refer to Procedure 006-026.

Static injection timing is not correct

Check the static injection timing. Refer to Procedure 006-025.

Camshaft end clearance is excessive

Check the camshaft end clearance. Refer to Procedure 001-065.

Cylinder head valve leak

Check the cylinder head for fuel leaks between the valves and valve seats. Refer to Procedure 002-004.

Internal engine damage

Analyze the oil and inspect the filters to locate an area of probable damage. Refer to Procedure 007-002. Remove the oil pan and inspect for damaged camshaft, cam followers, push rods, pistons, and liners. Refer to Procedure 007-025.