Can you calibrate a PT pump or injectors without a test bench? No – not properly. While you can mechanically adjust injector plunger travel on the engine (using a dial indicator for overhead adjustments), true calibration requires a test bench because: Fuel flow must be measured at multiple RPM points Injector-to-injector variation must be balanced within tight tolerances (often ±2–3 mL per 1000 strokes) Governor breakpoints and droop require dynamic testing AFC response needs controlled pressure ramping Field adjustments can get an engine running, but only a test bench ensures performance, fuel economy, and emissions compliance. https://www.cq-longshine.com/cummins-pt-test-bench