Savana 3500 V8-6.6L DSL Turbo VIN 6 (2007)
Fuel Injector: Component Tests and General Diagnostics
Fuel Injector Balance Test with Tech 2
Diagnostic Instructions
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Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
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Review Strategy Based Diagnosis for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The fuel injector balance test is performed when a misfire, knock, excessive smoke, or rough running condition exists with no electrical DTCs. This test
uses the Balance Rate and Cylinder Power Balance test to identify cylinders that are not producing the designed power output. The balance rate
adjustments are utilized by the engine control module (ECM) only at idle. The balance rates are the fuel adjustments for each individual cylinder based
on the variations in engine crankshaft speed. The balance rates will change depending on if the transmission is in Neutral or Drive. During the Cylinder
Power Balance portion of the test, the ECM turns OFF individual injectors while the engine is running. The ECM adjusts for the drop in engine RPM
during cancellation and may not change on the scan tool display. The lack of power at the cancelled cylinder will feel like a misfiring cylinder or
vibration. If a fuel injector is turned OFF and there is a no difference felt when compared to the other cylinders, that cylinder is identified with the
concern. If the customer concern occurs during idle or during off-idle tip in acceleration, the balance rates are used to identify the cylinder with a fault
related to the fuel injector or engine compression.
Diagnostic Aids
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The Cylinder Power Balance Test may be performed at any engine speed or load from idle to wide open throttle (WOT). There is a 5-minute time
limit for each test.
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A high balance rate may be caused by a fuel injector or compression only if the ECM can control fuel pressure.
Circuit/System Verification
Important: If any DTCs other than DTC P0300-P0308 are set, Refer to Diagnostic Trouble Code (DTC) List - Vehicle. See: Computers and
Control Systems/Testing and Inspection/Diagnostic Trouble Code Descriptions
1. Start and run the engine until the coolant temperature is more than 82°C (180°F). Turn OFF all accessories.
2. Perform the fuel pressure regulator test, Refer to Fuel Pressure Regulator Diagnosis. See: Computers and Control Systems/Testing and
Inspection/Component Tests and General Diagnostics/Fuel Pressure Regulator Diagnosis
3. With a scan tool, command the Balance Rate Monitor ON. Balance rates should be between +4 cu.mm and -6.9 cu.mm in Park or Neutral.
Important:
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The Cylinder Power Balance Test must be performed under the conditions for which the customer concern occurred.
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Do not operate the cruise control during this test. Cruise control may cause a brief surge of engine speed after the completion of the
test.
Perform the Cylinder Power Balance Test with a scan tool. During cylinder cancellation a noticeable power difference will feel like a misfiring
cylinder or vibration.
Circuit/System Testing
Important:
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You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
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A fuel injector leak into the combustion chamber may result in mechanical damage to the cylinder. If any fuel spray comes out of a glow
plug hole during the compression test, replace the fuel injector of the affected cylinder.
Perform the engine compression test. Refer to Engine Compression Test. See: Tune-up and Engine Performance Checks/Compression Check/Testing
and Inspection
If the compression indicated any of the cylinders had low compression, Refer to Symptoms - Engine. See: Engine, Cooling and Exhaust/Engine/Testing
and Inspection/Symptom Related Diagnostic Procedures/- Symptoms - Engine Mechanical
Important:
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Failure to correctly identify the cylinder positions may result in the replacement of the wrong injector.
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During replacement of the injectors, inspect the inlet and outlet fittings for corrosion or contamination. Refer to Contaminants-in-Fuel
