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The accuracy of the injection rate meter based on W. Zeuch's method in the measurement of multiple injection rate and amount was calibrated using a small cam driven piston that is driven by an electric motor. For the pre- or early-injection, a sensor with a high sensitivity can be applied to measure the small pressure increase due to the small injection amount. In case of the multiple injection that has the post and/or late injection, a pressure sensor with a low sensitivity must cover not only the large pressure increase due to the main injection but also the small pressure increase due to the post and/or late injection because the output of the high sensitivity sensor is saturated after the main injection. So the linearity of the low sensitivity pressure sensor was calibrated with the cam driven piston prior to the experiment with the actual injection system.

An experimental evaluation of the reliability of the Zeuch's method was carried out. The following were derived: 1) cavitation limits the minimum back pressure available; 2) the injection rate measured by the Zeuch's method agrees with that by the W.Bosch's method; 3) the effect of dynamic pressure of the injected fuel jet has a negligible effect on the pressure sensor which is attached to the chamber wall; and 4) the high-frequency noise after the end of injection observed in the Zeuch's measurement can be effectively removed by either a low-pass filter or an inverse Fourier transform processing.