The present invention provides a valve actuation system for an internal combustion engine. The valve actuation system of the present invention may provide an increased range of auto-ignition operation by providing a valve re-opening mechanism to provide products of combustion into the cylinder to increase the thermal efficiency and stability of the auto-ignition combustion process. The present invention allows the poppet valve re-opening timing, lift and duration to be tailored to specific engine architecture and operating conditions. Additionally, the present invention provides a method of re-opening a poppet valve of an internal combustion engine.