Engine Controls - WDS Power Balance Test Service Tip
TSB 04-15-1308/09/04
6.0L DIAGNOSIS USING THE WDS POWER BALANCE
TEST - SERVICE TIP
FORD:
2003-2005 Excursion, F-Super Duty
2004-2005 Econoline
ISSUE
The WDS Power Balance test can effectively be used to support other diagnostic routines, such as the Mass Fuel Desired Test, that have identified a low contributing cylinder. The test should not be performed by itself to determine what repair should be made.
ACTION
Prior to performing a Power Balance test follow the Performance Diagnostic Procedures (PC/ED, Section 4) that are appropriate for the vehicle symptom to ensure no other performance concerns are present. If the Power Balance test is needed use the following procedure to perform the test.
SERVICE PROCEDURE
NOTE
THE POWER BALANCE TEST IS CAPABLE OF FALSELY IDENTIFYING A WEAK CYLINDER. A WEAK CYLINDER MAY CAUSE NEIGHBORING CYLINDERS (IN THE FIRING ORDER) OR COMPANION CYLINDERS (180 DEGREES OPPOSED) TO APPEAR WEAK WHEN THEY ARE NOT. FIGURE 1 SHOWS THE CYLINDER NUMBER DESIGNATIONS AND FIRING ORDER. FIGURE 2 SHOWS HOW IT CAN APPEAR THAT THE NUMBER ONE (1) CYLINDER IS A LOW CONTRIBUTING CYLINDER, WHEN IN REALITY, NUMBER ONE (1) CYLINDER IS GOOD AND IS RECOVERING FROM NUMBER EIGHT (8) CYLINDER BEING LOW.
NOTE
THE POWER BALANCE TEST SHOULD NEVER BE USED TO SUPPORT THE REPLACEMENT OF MORE THAN ONE INJECTOR AT A TIME. FOLLOWING THE REPLACEMENT OF AN INJECTOR, BE SURE TO ROAD TEST THE VEHICLE TO ENSURE ALL AIR HAS BEEN PURGED PRIOR TO REEVALUATION.
NOTE
IF IDLE QUALITY IS ACCEPTABLE INJECTORS SHOULD NOT BE REPLACED BASED ONLY ON THE RESULTS OF A POWER BALANCE TEST.
1. Bring the engine temperature up to the appropriate range, based on the description of the concern.
NOTE
AN INJECTOR CAN APPEAR TO BE CONTRIBUTING EQUALLY AT ONE TEMPERATURE RANGE AND HAVE LOW CONTRIBUTION AT A DIFFERENT TEMPERATURE RANGE.
2. Connect WDS to the vehicle and start a Power Balance test with the transmission in neutral or park.
NOTE
DO NOT PERFORM THE POWER BALANCE TEST WITH THE TRANSMISSION IN GEAR, AS THIS MAY DISTORT THE TEST RESULTS.
3. With the Power Balance Test running, switch to Data Logger and select a PID for injector 1-8 (it does not matter which one).
4. Highlight the injector PID and take active command of the PID. DO NOT SHUT THE INJECTOR OFF.
NOTE
THE FUEL INJECTION CONTROL MODULE (FICM) HAS A FUEL CORRECTION FEATURE THAT IS USED TO SMOOTH ENGINE IDLE BY ADDING FUEL TO ANY CYLINDER THAT LOWERS ENGINE SPEED DURING A FIRING CYCLE. STEP 4 DISABLES THE FICM'S FUEL CORRECTION FEATURE FOR APPROXIMATELY ONE (1) MINUTE.
5. Using the tabs at the top of the screen switch back to the Power Balance test and identify the lowest contributing cylinder.
6. If a low contributing cylinder is identified, perform an Injector Electrical Test and a Relative Compression Test with WDS to check for base engine concerns.
7. If no other problems are found, replace ONLY the injector for the lowest contributing cylinder.
8. Road test the vehicle to ensure all air has been purged and reevaluate to determine if further repair is needed.
WARRANTY STATUS: INFORMATION ONLY
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