An engine control system for a vehicle includes a pressure determination module, an adjustment determination module, a target determination module, and a pump control module. The pressure determination module determines a first pressure for a hydraulic fluid provided to fully flexible intake and exhaust valve actuators of an engine. The adjustment determination module determines a pressure adjustment for the first pressure based on a pressure within a cylinder. The target determination module determines a target pressure for the hydraulic fluid based on the first pressure and the pressure adjustment. Based on the target pressure, the pump control module controls a hydraulic fluid pump for an opening timing of an exhaust valve of the cylinder.