An engine assembly may include a voltage source and an oxygen pump assembly. The oxygen pump assembly may include an intake conduit and an oxygen pumping mechanism. The intake conduit may be in fluid communication with an air supply and an intake manifold. The oxygen pumping mechanism may include an oxygen ion conducting cell, a first electrode in electrical communication with the voltage source and a second electrode in electrical communication with the voltage source. The first electrode may be disposed on a first side of the cell and may be exposed to an interior of the intake conduit. The second electrode may be disposed on a second side of the cell and isolated from the interior of the conduit. The oxygen pumping mechanism may remove oxygen from an air flow within the interior of the intake conduit based on a voltage applied across the cell by the voltage source.