The paper describes a method to measure injector opening and closing lag times based on measuring the vibration in the axis of movement of a valve. There are also some results of the studies on a plate injector. Analysing the measurements obtained, it is demonstrated that opening and closing lag times can be determined much more precisely by measuring vibration than by the method based on analysing gas pressure directly behind an injector. The authors have noted the greater repeatability of standard deviation expressed as the smaller standard deviation of the lag times specified and the easy application of this method for stand testing. Consequently, this method can determine these times in a simple and precise way.