Fuel Injector Balance Test
WARNING: This page is about a different variant/trim than selected.
NOTE:
- 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.
- Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.
Fuel Injector Balance Test with Scan Tool
- Verify the correct low side fuel pressure. Refer to Fuel System Diagnosis .
- Engine idling, verify the scan tool Fuel Rail Pressure Sensor parameter is approximately 3 MPa (435 psi).
- Select the Fuel Injector Balance function within the Control Functions menu of a scan tool.
- Select and test an injector. Repeat for each injector.
- Obtain and record a pressure drop value for each injector.
- Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
- Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
- Multiply the average pressure drop by 0.20. This is the acceptable variance from the average pressure drop, 20 percent.
- Verify the difference between any individual pressure drop and the average pressure drop is not greater than the acceptable variance.
- If greater than the acceptable variance
Replace the appropriate Q17 Fuel Injector(s).
- Go to next step: If within the acceptable variance
- If greater than the acceptable variance
- Perform the Fuel Injector Circuit Diagnosis .
NOTE:
The engine speed must be between 600 - 1000 RPM to perform this test.
NOTE:
For engines with 2 banks of cylinders, only measure average pressure drop on cylinders that are on the same bank.