Circuit System Testing

Fuel Injector Balance Test with Active Fuel Injector Tester

1. Ignition OFF, all vehicle systems OFF. Install the CH-47976  Active Fuel Injector Tester and the CH-47976-500  Active Fuel Injection Tester (AFIT) SIDI Adapter Kit, refer to the Active Fuel Injector Tester User Guide. It may take up to 2 minutes for all vehicle systems to power down.
2. Turn ON the Active Fuel Injector Tester and select the vehicle.
3. Ignition ON, perform the Injector Test with the Active Fuel Injector Tester.
   • If the Active Fuel Injector Tester aborts testing due to fuel pressure or fuel leak down 

     Refer to Fuel System Diagnosis .

   • If the Active Fuel Injector Tester does not abort testing 
4. Compare the test results with the appropriate recommended tolerance.
   • If any fuel injector exceeds the recommended tolerance 

     Replace the appropriate Q17 Fuel Injector(s).

   • If all fuel injectors are within the recommended tolerance 
5. Perform Fuel Injector Circuit Diagnosis .

Fuel Injector Balance Test with Scan Tool

1. Ignition ON.
2. Command the Fuel Pump Enable ON with a scan tool.
3. Verify the fuel pressure is between 320 - 580 kPa (46 - 84 PSI) with the fuel pump running.
   • If not within 320 - 580 kPa (46 - 84 PSI) 

     Refer to Fuel System Diagnosis .

   • If within 320 - 580 kPa (46 - 84 PSI) 
NOTE:

The fuel pressure may vary slightly when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

4. Verify the fuel pressure does not decrease greater than 34 kPa (5 PSI) within 1 minute.
   • If greater than the specified value 

     Refer to Fuel System Diagnosis .

   • If less than the specified value 
5. Engine idling.
6. Verify the scan tool Fuel Rail Pressure Sensor 1 parameter is between 1.9 - 5.0 MPa (276 - 725 PSI).
   • If not between 1.9 - 5.0 MPa (276 - 725 PSI) 

     Refer to Fuel System Diagnosis .

   • If between 1.9 - 5.0 MPa (276 - 725 PSI) 
NOTE:

The engine speed must be between 600 - 1, 000 RPM to perform this test.

7. Select the Fuel Injector Balance function within the Control Functions menu of a scan tool.
8. Select and test a Q17 Fuel Injector. Repeat for each Q17 Fuel Injector.
9. Obtain and record a pressure drop value for each Q17 Fuel Injector.
10. Add all of the individual pressure drop values except for the fuel injector suspected of being faulty. This is the total pressure drop.
11. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
12. Multiply the average pressure drop by 0.20. This is the acceptable variance from the average pressure drop, 20%.
13. 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 Q17 Fuel Injector.

    • If within the acceptable variance 
14. Perform Fuel Injector Circuit Diagnosis .