6B. Power Balance Test

6b. Power Balance Test

Note: Do not replace the fuel injectors based only on the results of the Power Balance Test. Always verify the fuel delivery system the high pressure oil system the fuel injector electrical system and the base engine system functions are operating correctly.

Note: Before carrying out the Power Balance Test allow the engine to stabilize at the temperature necessary to recreate the symptom. Access the PCM and record the freeze frame data. The freeze frame data contains information which can be used to recreate original conditions that caused the symptom. Refer to Freeze Frame Data for more information.

Note: The contributing power cylinders that immediately follow the non-contributing power cylinders in the firing order may be affected. The affected power cylinders may not be able to fully recover the crankshaft speed causing them to display below average contributing power cylinders and to be incorrectly identified as the non-contributing power cylinder. Therefore only the cylinders that deviate the most from the average should be identified as the non-contributing power cylinder. Single or inconsistent non- contributing power cylinder traces may be caused by a natural variation in the crankshaft speed and should be ignored.

Note: Disregard any DTCs set as a result of the Power Balance Test.

Note: If the fuel injectors have been removed or the high pressure oil system has been repaired it may be necessary to operate the vehicle and carry out a minimum of 12 short high demand acceleration cycles to purge air from the high pressure oil system.

Note: If the engine runs rough between 12OO RPM and 23OO RPM follow the Check Valve Operation test in this section before carrying out the Power Balance Test.

Note: If the engine does not start during this procedure verify the batteries are fully charged plug in the block heater and cycle the key several times to activate the glow plugs.

Note: If the vehicle is equipped with a power take-off (PTO) system or auxiliary idle control it must be turned off to carry out the Power Balance Test.

Note: Verify the engine oil level and quality. Refer to Check Engine Oil Level in this section.

Purpose:

The purpose of this test is to determine the power contribution each cylinder provides to the crankshafi.

Power Balance Test

^ Carry out the Power Balance Test.
^ Monitor individual cylinder contribution and record the consistently non-contributing power cylinders.










Recommended Procedure:

^ Turn off all accessones.
^ Turn off the PTO if equipped.
^ Key ON engine running.
^ Start the Power Balance Test and monitor the cylinder power contribution for 8 seconds. Identify and record the cylinders with 15 RPM or more above or below the average engine RPM.
^ While the Power Balance Test is running use the injector cancel mode to turn off the idle compensation strategy. Monitor power contribution for 8 seconds. Identify and record the non-contributing power cylinders.
^ While the Power Balance Test is running with the idle compensation strategy turned off increase the engine speed to between 800 and 900 RPM. Monitor power contribution for 8 seconds and identify and record the non-contributing power cylinders.

Possible Causes:

^ Broken or worn compression ring pack
^ Damaged cylinder walls
^ Valvetrain damage
^ Fuel injector 0-ring seals
^ Fuel injectors
^ Oil change past due
^ Aerated fuel
^ Low fuel pressure

Tools Required:

Scan tool