Abstract: Process for determining the starting point of fuel injection in internal-combustion engines having a fuel-injection nozzle with a housing and a needle valve and a displacement limited by a stroke limiter, comprising the steps of observing and consecutively registering vibrations and/or noise phenomena arising from abutments of the needle in the valve against the stroke limiter, and selecting the leading branch or ascending flank of a first half-wave signal from that vibration, the registering being accomplished with a sensing element placed at least in the vicinity of the nozzle housing. Several additional, optional features are disclosed.