Electronic Control System Signature, ISX and QSX15 Engines – Engine Power Output Low

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.

Engine is misfiring

Refer to the Engine Runs Rough or Misfires 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 protection fault code(s) inactive

View the fault codes and the engine protection data with an electronic service tool. Refer to the appropriate electronic service tool manual. Refer to the corresponding fault code in Section TFSection TF for fault code troubleshooting.

Accelerator pedal or lever is restricted or malfunctioning

Check the percent accelerator pedal or lever reading on an electronic service tool. Verify that it reads 100 percent with the accelerator pedal depressed and 0 percent when released. Calibrate the accelerator if possible. Replace the accelerator pedal if necessary. Refer to the OEM service manual.

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 (ECM Calibration Code) in Section 19.

Programmable parameters or selected features are not correct

Check the programmable parameters and the selected features with an electronic service tool. Set the parameters and features again if necessary. Refer to
Procedure 019-078 (Programmable Features and Parameters Not Correct) in Section 19.

Fuel inlet restriction

Check for fuel inlet restriction. Refer to
Procedure 006-020 (Fuel Inlet Restriction) in Section 6 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 (Fuel Drain Line Restriction) in Section 6 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Air in the fuel system

Check for air in the fuel system. Refer to Procedure 006-003 (Air in Fuel) in Section 6 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

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 Procedure 018-002 (Fuel Recommendations and Specifications) in Section V of the Operation and Maintenance Manual, Bulletin 3666251.

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 (Air Intake Restriction) in Section 10 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Air intake or exhaust leaks

Inspect the air intake and exhaust systems for air leaks. Refer to
Procedure 010-024 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 (Exhaust Restriction) in Section 11 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Charge air cooler is restricted or leaking

Inspect the charge air cooler for air restrictions or leaks. Refer to
Procedure 010-027 (Charge-Air Cooler) in Section 10 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Ambient air temperature sensor is malfunctioning (if equipped)

Check the ambient air temperature sensor. Refer to
Procedure 019-004 (Barometric Air Pressure Sensor) in Section 19.

Vehicle speed sensor (VSS) or circuit is malfunctioning

Check the vehicle speed sensor and circuit. Refer to
Procedure 019-090 (Vehicle Speed Sensor, Digital Input) in Section 19,
and Procedure 019-091 (Vehicle Speed Sensor, Magnetic Pick Up) in Section 19.

Vehicle parasitics are excessive

Check for transmission malfunctioning, cooling fan operation cycle time, and engine-driven units. Refer to the OEM service manual.

Lubricating oil level is above specification

Check the oil level. Verify the dipstick calibration and oil pan capacity. Fill the system to the specified level. Refer to
Procedure 007-009 (Lubricating Oil Dipstick) in Section 7
or Procedure 007-025 (Lubricating Oil Pan) in Section 7 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Turbocharger is not correct

Check the turbocharger part number and compare it to the Control Parts List (CPL), Bulletin 3379133 or 4021327. Replace the turbocharger if necessary. Refer to
Procedure 010-033 (Turbocharger) in Section 10 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Turbocharger is malfunctioning

Monitor the turbocharger boost pressure with an electronic service tool. Refer to
Procedure 010-033 (Turbocharger) in Section 10 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 (Turbocharger Wastegate Actuator) in Section 10 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Engine is operating above recommended altitude

Engine power decreases above recommended altitude. Refer to the Engine Data Sheet for specifications.

Engine brake adjustment is not correct

Adjust the engine brakes. Refer to
Procedure 020-004 (Engine Brake Assembly) in Section 20 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 (Engine Brake Assembly) in Section 20 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 (Overhead Set) in Section 3 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 (Fueling Actuator) in Section 19
or Procedure 019-111 (Timing Actuator) in Section 19.

Injector is malfunctioning

Perform the automated cylinder performance test. Replace injectors as necessary. Refer to
Procedure 006-026 (Injector) in Section 6 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 (Injector) in Section 6 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Injector o-rings are damaged or missing

Remove and check the injectors. Replace the injector o-rings. Refer to
Procedure 006-026 (Injector) in Section 6 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Injectors are not correct

Remove the injectors and compare the part numbers to the Control Parts List (CPL), Bulletin 3379133 or 4021327. Replace the injectors if necessary. Refer to
Procedure 006-026 (Injector) in Section 6 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Debris in the fuel passages

Check the fuel tubes and fuel manifold for debris. Refer to
Procedure 006-024 (Fuel Supply Lines) in Section 6 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.

Tachometer or speedometer is not calibrated or is malfunctioning

Compare the vehicle tachometer and speedometer readings with an electronic service tool reading. Check the calibration values for the flywheel teeth, rear axle ratio, and tire revolutions. Adjust the values if necessary. Refer to the appropriate electronic service tool manual. Calibrate or replace the tachometer or speedometer as necessary. Refer to the OEM service manual.

Internal engine damage

Analyze the oil and inspect the filters to locate an area of probable damage. Refer to
Procedure 007-083 (Lubricating Oil and Filter Analysis) in Section 7 in the Troubleshooting and Repair Manual, Signature, ISX and QSX15 Engines, Bulletin 3666239.