A set of electro-hydraulic variable valve system (EHVVS) was investigated in order to research the characteristics of additional valve lift under different oil pressures and control pulses. The results indicate that the valve closing depends on the control pulse width

and the oil pressure can affect the speed of valve opening at the additional lift. The max value and fluctuation of the additional valve lift are mainly decided by the oil pressure

and the control pulse width has a little effect on the fluctuation. When the oil pressure is 3.5 MPa

the fluctuation is small

suggesting the valve works stable. The research reveals that the EHVVS has a fast response to valve opening and closing.