GxT V055-01 Diagnostic Analyzer - Manual (Page 19)

19
Fuel Injector Drive Test
No readings will be displayed if there are no amps pulses,
or if the pickup is reversed, or around both wires of an
injector.
Peak Amps (PkAmp) shows the peak current driving
the injector. It is regulated by the driver. Typical peak
readings for one injector are 4 amps for current regulated
drivers, and 0.7 amps for resistance limited drivers. Compare one driver bank to another.
Build Time, or ramp time in milliSeconds (mS) is affected by the solenoid and the pintle movement. Slightly
shorter-than-normal Build Time can be caused by a solenoid winding short or an injector that is stuck.
Slightly longer could be from a bad driver or wire connection. Typically, build time is 1.3 mS.
Pulse Width is shown on the lower display line. It lets you see if the injector is actively driven. Use
momentary wide open throttle to see the Min and Max range. The center reading shows what is presently
happening. The NEXT key clears the Min and Max so they can begin accumulating again.
FUEL INJECTION CIRCUIT TYPES
Sequential - Each injector has a separate driver and can be driven independently of the other injectors.
The build time currents can overlap on these systems; for valid readings check each injector separately.
Pairs - There is one driver for each pair of injectors. The current readings, as measured through the
common supply wire, will be twice the reading expected for a single injector.
Banks - Half of cylinders are driven alternately. The current readings as measured through the common
supply wire will be 2, 3, or 4 times the reading expected for a single injector.
Fuel Injection Troubleshooting Chart
Fuel Injector Hookup
Amps Build Sequential
None None Open circuit, check continuity
Low Long Wiring, connections, or driver
High Short Shorted Winding
Amps Build Banked or Paired
None None Open circuit or bad driver
High ------- Shorted winding
Normal Short Shorted winding, Driver OK
High Long Driver not Limiting
Low Long Open, high resistance, or
bad driver