Abstract: A method of using an amorphous carbon-based coating to extend the operating life of a fuel injector having a needle operating within a valve body, the valve body, the valve and body having steel surfaces subject to repeated impact and sliding friction contact over the operating life of the injector. The method comprises (a) providing the steel surfaces of at least one of the needle and body with an ion implanted stabilized amorphous carbon-based coating in a thickness of 1-10 micrometers, the coating having low internal stresses and low coefficient of friction independent of humidity and being stabilized by the presence of up to 30% by weight of carbide forming material selected from the group of silicon, titanium and tungsten, and (b) repeatedly and rapidly actuating the fuel injector in time periods of 0.5-1.