How to test engine injector

Three tests can be used to determine which cylinder or injector is
malfunctioning:
Injector Solenoid Test
This test is performed while the engine is stopped. The injector solenoids
can be tested automatically with the ET Service Tool using the Injector
Solenoid Test. This function individually tests each solenoid in sequence
and indicates if a short or open circuit is present.
Cylinder Cut-out (Manual test)
This test is performed while the engine is running at any speed. The
105 Volt pulse can be individually cut out to aid in troubleshooting
misfire problems in the injector and cylinder.
Automatic Injector Test
This test is performed with the ET Service Tool while the engine is
running at any speed. The test makes a comparative evaluation of all
injectors and numerically shows the results. The test enables an
on-engine evaluation of the injectors. (This test cannot be performed
using the ECAP.)
A satisfactory test of all injector solenoids without any diagnostic
messages indicates that a mechanical problem in the cylinder probably
exists.