Fuel Injector Balance Test (LF1, LFW)
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Fuel Injector Balance Test (LF1, LFW)
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Circuit/System Description
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The fuel injector balance test is performed while the engine is running at idle. The scan tool pressurizes the fuel rail to a predetermined pressure before each injector is pulsed for a precise amount of time allowing a measured amount of the fuel to be injected. This causes a drop in the system fuel pressure that is recorded and used to compare each injector.
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Monitoring the Current Misfire Counters may help to isolate the fuel injector that is causing the condition.
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Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
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Note
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DO NOT perform this test if the engine coolant temperature (ECT) is above 60°C (140°F). Irregular fuel pressure readings may result due to hot soak fuel boiling.
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Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
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Fuel Injector Balance Test
2.
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Note
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The engine speed must be between 600-1000 RPM to perform this test.
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Engine running at normal operating temperature. With a scan tool, select the Fuel Injector Balance function within the Output Controls menu.
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3.
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Select and test an injector. Repeat for each injector in order to obtain a pressure drop value for each injector.
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4.
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After all injectors are tested, record the fuel pressure drops.
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5.
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Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
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6.
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Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
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7.
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Multiply the average pressure drop by 0.20. This is the acceptable variance from the average pressure drop, 20 percent.
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8.
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If the difference between any individual pressure drop and the average pressure drop is more than the acceptable variance, replace the fuel injector.
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Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.