What this test proves

Compare relative flow using equal injector commands and equal starting rail pressure. This is not a GDI or diesel injector test.

Tools

  • Approved injector balance function or compatible pulse tool
  • Low-pressure fuel gauge
  • Application-specific command limits

Preparation and precautions

  • Confirm the system supports this test. Follow engine-off, ignition-disable and fuel-pressure requirements.
  • Limit repeated pulses to avoid flooding or liquid accumulation. Never substitute this method for a piezo or high-pressure injector procedure.

Connections

  • Connect the gauge at the approved port and the scan tool or injector tool exactly as specified.

Equipment settings

  • Use the same prescribed pulse duration/count and starting pressure for every injector.

Test sequence

  1. Build the specified initial pressure.
  2. Pulse one injector and record pressure drop.
  3. Restore the same starting pressure before each remaining injector.
  4. Compare drops within the specified tolerance.
  5. Follow the OEM clearing/restoration procedure before restarting.

Expected signal / readings

Equivalent injectors should produce comparable pressure drops under identical conditions.

Interpreting results

  • A smaller drop may indicate reduced flow or missing activation; a larger drop may indicate excess flow.
  • Pressure drift, regulator behavior and unequal starting pressure can invalidate comparison.

Common mistakes

  • Repeatedly pulsing a flooded cylinder
  • Unequal starting pressure
  • Treating balance as proof of spray quality