C-2A ~ Injector Balance

Chart C-2A Injector Balance Test:

Injector Balance Test:

Injector Balance Test Example:

The injector balance tester is a tool used to turn the injector on for a precise amount of time, thus spraying a measured amount of fuel into the manifold. This causes a drop in fuel rail pressure that we can record and compare between each injector. All injectors should have the same amount of pressure drop (- 10 kPa). Any injector with a pressure drop that is 10 kPa (or more) greater or less than the average drop of the other injectors should be considered faulty and replaced.

NOTES:
^ It will be necessary to remove the intake plenum to perform this procedure. Refer to intake plenum remove procedure in this section. It will also be necessary to install the Intake Manifold Diagnostic Plate J 39185 to enable the engine to be run with the plenum removed. Refer to Powertrain Management/Fuel Delivery and Air Induction/Intake Air Plenum/Service and Repair.

^ The entire test should NOT be repeated more than once without running the engine to prevent flooding. (This includes any retest on faulty injectors). To run the engine with the intake plenum removed use the Intake Manifold Diagnostic Plate.


STEP 1
- Engine "cool down" period (10 minutes) is necessary to avoid irregular readings due to "Hot Soak" fuel boiling. With ignition "OFF" connect fuel gauge J 347301 or equivalent to fuel pressure tap. Wrap a shop towel around fitting while connecting gage to avoid fuel spillage. Refer to Powertrain Management/Fuel Delivery and Air Induction/Testing and Inspection/Procedures.

- Disconnect harness connectors at all injectors, and connect injector tester J 34730-3, or equivalent, to one injector. Follow manufacturers instructions for use of adaptor harness. Ignition must be "OFF" at least 10 seconds to complete engine control module shutdown cycle. Fuel pump should run about 2 seconds after ignition is turned "ON". At this point, insert clear tubing attached to vent valve into a operation. Repeat this step until all air is bled from gauge.


STEP 2
- Turn ignition "OFF" for 10 seconds and then "ON" again to get fuel pressure to its maximum. Record this initial pressure reading. Energize tester one time and note pressure drop at its lowest point (Disregard any slight pressure increase after drop hits low point). By subtracting this second pressure reading from the initial pressure, we have the actual amount of injector pressure drop.


STEP 3
- Repeat step 2 on each injector and compare the amount of drop. Usually, good injectors will have virtually the same drop. Retest any injector that has a pressure difference of 10 kPa, either more or less than the average of the other injectors on the engine. Replace any injector that also fails the retest. If the pressure drop of all injectors is within 10 kPa of this average, the injectors appear to be following properly.