Fuel Injector: Testing and Inspection
FUEL INJECTOR BALANCE TEST WITH TECH 2CIRCUIT DESCRIPTION
The Fuel Injector Balance Test is performed when a misfire, knock, excessive smoke, or rough running condition exists with no electrical diagnostic trouble codes (DTCs). During the test the engine control module (ECM) turns OFF individual injectors while the engine is running and the scan tool displays engine RPM. If a fuel injector is turned OFF and there is a different engine speed change observed on the scan tool when compared to the other cylinders, that cylinder has a fuel injector or engine compression condition. If there is a balance rate of more than 4 cu.mm or less than -4 cu.mm on any of the cylinders, that cylinder has a fuel injector or engine compression condition. If a fuel injector is turned OFF and the engine noise or smoke disappears, that cylinder has a fuel injector or engine compression condition.
TEST DESCRIPTION
Step 1:
Steps 2-4:
Steps 5-6:
Steps 7-9:
The numbers below refer to the step numbers on the diagnostic table.
3. A balance rate between -4 cu.mm and +4 cu.mm will not cause a driveability concern. A balance rate less than -4 cu.mm, between 4 cu.mm and 14 cu.mm will cause a driveability concern without any DTCs. A balance rate of more than 15 cu.mm will set a DTC.
4. This step determines if the ECM can control a stable fuel pressure. A high balance rate may be caused by a fuel injector or compression only if the ECM can control fuel pressure.