{Scan Tool} Fuel Injector Balance Test
WARNING: This page is about a different variant/trim than selected.
- Ignition/Vehicle - Off
- Disconnect the electrical connector: X3@K20 Engine Control Module
- Test for 1 to 3 ohms between the test points:
- {Q17A Fuel Injector 1} Control circuit terminal 72 & Control circuit terminal 52
- {Q17B Fuel Injector 2} Control circuit terminal 66 & Control circuit terminal 46
- {Q17C Fuel Injector 3} Control circuit terminal 69 & Control circuit terminal 49
- {Q17D Fuel Injector 4} Control circuit terminal 65 & Control circuit terminal 45
- {Q17E Fuel Injector 5} Control circuit terminal 71 & Control circuit terminal 51
- {Q17F Fuel Injector 6} Control circuit terminal 67 & Control circuit terminal 47
- {Q17G Fuel Injector 7} Control circuit terminal 70 & Control circuit terminal 50
- {Q17H Fuel Injector 8} Control circuit terminal 68 & Control circuit terminal 48
- If not between 1 and 3 ohms
Replace the component: Q17 Fuel Injector
- Go to next step: If between 1 and 3 ohms
- Ignition - On/Vehicle - In Service Mode
- Perform the scan tool control function: Fuel Pump Enable - On - Command the function On several times.
Verify the scan tool parameter: Fuel Pressure Sensor = 320 to 608 kPa (46 to 88 PSI)
- If not between 320 and 608 kPa (46 and 88 PSI)
Refer to: Fuel System Diagnosis
- Go to next step: If between 320 and 608 kPa (46 and 88 PSI)
- If not between 320 and 608 kPa (46 and 88 PSI)
- Engine - Idling
- Verify the scan tool parameter: Fuel Rail Pressure Sensor = 1.9 to 5.0 MPa (276 to 725 PSI)
- If not between 1.9 and 5.0 MPa (276 and 725 PSI)
- Go to next step: If between 1.9 and 5.0 MPa (276 and 725 PSI)
- Engine - Running@600 to 1, 000 RPM
- Perform the scan tool control function: Fuel Injector Balance - Cylinder 1-8 - Enable - One at a time
- Record the value - Fuel Pressure Drop - After each component test.
- Add all the recorded values, except the suspected faulty component. This is the total pressure drop.
- Perform the following steps:
- Total pressure drop÷Number of components = Average pressure drop
- Average pressure dropx 0.20(20%) = Acceptable variance between components
Verify the difference between a single pressure drop and the average pressure drop is not greater than the acceptable variance.
- If greater than the acceptable variance
Replace the component: Q17 Fuel Injector
- Go to next step: If within the acceptable variance
- All OK.
NOTE:
This diagnostic assumes there are no circuit faults.
NOTE:
The component's temperature should be 19 to 21°C (66 to 70°F) while testing.
NOTE:
The fuel pump may need to be commanded On a few times in order to obtain the highest possible fuel pressure.
NOTE:
Perform the following test for all 8 components.
NOTE:
For engines with 2 cylinder banks, only measure the average pressure drop across cylinders that are on the same bank.