Symptom Tree t087
| Cause | Correction |
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Interview the operator to verify the complaint |
Refer to Fuel Consumption General Information and Customer Complaint Form in Procedure t00-004 (Troubleshooting Overview) at the end of this section. Follow the instructions on the form before continuing with this tree. |
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Operator technique is not correct |
Explain correct engine operation to the operator. Refer to Procedure 101-015 the Operation and Maintenance Manual, Signature and ISX Engines, Bulletin 3666251 or |
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VE/VMS® analysis uses incorrect data |
Review the VE/VMS® data and compare to the vehicle and engine specifications. Do not use more than 20 percent for the Aero value. Refer to the VE/VMS® User’s Manual. |
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Equipment and environmental factors are affecting fuel consumption |
Consider ambient temperatures, wind, tire size, axle alignment, routes, and use of aerodynamic aids when evaluating fuel consumption. |
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Drivetrain is not correctly matched to the engine |
Check for correct gearing and drivetrain components. Refer to the OEM service manual. |
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Electronic fault codes active or high counts of inactive fault codes |
Refer to Section TF or the Troubleshooting and Repair Manual, Electronic Control System, Signature, ISX and QSX Engines, Bulletin 3666259, |
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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 the electronic service tool manual. |
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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 |
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Fuel leak |
Check the fuel lines, fuel connections, and fuel filters for leaks. Check the fuel lines to the supply tanks. Refer to the OEM service manual. |
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Hubometer or odometer is miscalibrated |
Check the hubometer and odometer calibrations. Calibrate or replace the hubometer or odometer, if necessary. Calculate fuel consumption with new mileage figures. |
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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 |
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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 Procedures 007-009 (Lubricating Oil Dipstick) in Section 7 and |
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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 |
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Vehicle speed sensor (VSS) is not correct |
Use an electronic service tool to monitor the vehicle speed while the vehicle is not moving. Refer to the appropriate electronic service tool manual. If necessary, install the correct VSS. Refer to Procedure |
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Vehicle speed sensor (VSS) or circuit is malfunctioning |
Check the vehicle speed sensor and circuit. Refer to Procedures |
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Vehicle speed sensor (VSS) tampering has occurred |
Check the vehicle speed sensor and circuit for tampering. Check for Fault Code 242. Repair the circuit as necessary. Refer to Procedures |
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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 |
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Exhaust system restriction is not within specification |
Check the exhaust system for restrictions. Refer to Procedure |
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Injector is malfunctioning |
Perform the single-cylinder cutout test. Replace the injectors as necessary. Refer to Procedure |
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Turbocharger wastegate is malfunctioning (if equipped) |
Check the wastegate for correct operation. Refer to Procedure |
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Turbocharger is malfunctioning |
Monitor the turbocharger boost pressure with an electronic service tool. Refer to Engine Performance Troubleshooting in Section TT. Check the turbocharger variable geometry operation (if applicable). |
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Overhead adjustments are not correct |
Measure and adjust the overhead settings. Refer to Procedure |
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Internal engine damage |
Analyze the oil and inspect the filters to locate an area of probable damage. Refer to Procedure |
