Time-resolved current and voltage measurements for an inductive automotive spark system were made. The measurements were made in air for a range of charge time from 1-8ms, at ambient temperatures. Primary current was measured, so the primary energy can be calculated. Current and voltage signal of secondary circuit was detected, from which the spark energy and energy transformation efficiency can be calculated. Test results show that: when the charge time is 6ms, both the primary energy and spark energy reaches to saturation value, does not advanced any more with the charge time increasing; and the energy transformation efficiency is at an appropriate range.