Diesel Engine Injector Balance Rates All Showing Zero - kw 6.6 LB7 LLY rough idle miss misfire driveability inoperative P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

A 6.6L LLY or LB7 diesel engine equipped vehicle may be brought into the dealer for engine driveability concerns, rough running, or Engine Diagnostic Trouble Codes (DTCs). During diagnosis, a technician may find that all the cylinder balance rates are reading at zero. The Cylinder Injector Balance Rates may read zero at idle due to excessive variations in engine crankshaft speed or a false vehicle speed input.

Balance rate adjustments are utilized by the ECM only at idle. The balance rates are the fuel adjustments for each individual cylinder based on the variations in engine crankshaft speed.

1. Complete SI diagnostics for Rough, Unstable, or Incorrect Idle and Stalling.
2. Complete SI diagnostics for any DTCs found.
3. Inspect the fuel system for excessive contamination.
4. If the vehicle is equipped with a manual transmission, a worn or damaged Dual Mass Flywheel may cause excessive crankshaft speed variance. This will cause the cylinder balance rates to fluctuate or read zero. Diagnose and repair Dual Mass Flywheel concerns using current SI procedures.
5. Monitor the vehicle speed sensor signal ( VSS ) on the Tech 2. If the vehicle is not moving and vehicle speed is registered, the balance rates will be disabled. Diagnose and repair VSS concerns using current SI procedures.
6. If the cylinder balance rates are reading at zero on a automatic transmission equipped vehicle, apply the vehicle brakes, shift the vehicle into drive, and then monitor the balance rates. When the vehicle is in drive, the engine crankshaft speed will stabilize, and balance rates will begin to record current engine data. Diagnose the cylinder injector balance rates using current SI procedures.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

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