Injector Balance Test
The injector balance test is used to pulse the injector for a precise amount of time, spraying a measured amount of fuel in the intake manifold. As each injector is pulsed, a drop in fuel rail pressure occurs. This pressure drop can be recorded and compared to other injectors. An injector with a pressure drop of 1.5 psi (.11 kg/cm2 ) or more, greater than or less than other injectors, should be considered faulty.
NOTE:
Allow engine to cool down to avoid irregular readings due to "Hot Soak" fuel boiling. To prevent flooding, the INJECTOR BALANCE TEST should not be repeated more than once without starting and running engine.
CAUTION:
To avoid possible vehicle fire, wrap a shop towel around fitting to avoid fuel spillage.
- With ignition off, connect Fuel Pressure Gauge (J-34730-1) to pressure tap. Unplug harness connector at all injectors. Connect Injector Tester (J-34730-3) to one of the injectors.
- Follow manufacturer's instructions when installing adapter harness. Ignition should be turned off at least 10 seconds to complete ECM shutdown cycle.
- Turn ignition on. Fuel pump should run at least 2 seconds after ignition is turned on. Bleed air from gauge and hose to ensure accurate gauge reading. Repeat this procedure until all air is bled from system. Turn ignition off for at least 10 seconds.
- Turn ignition on again to bring fuel pressure to maximum. Record initial pressure reading. Energize tester one time and note pressure drop at lowest point.
- Disregard any slight pressure drop after low point is reached. Subtracting second pressure reading from initial reading indicates amount of injector pressure drop.
- Repeat step 4) on each injector and compare pressure drop. Recheck injectors not within pressure drop range. Replace injector(s) failing second check.
- If injectors are all okay, plug in harness connectors and review SYMPTOMS in H - TESTING W/O CODES article.