An engine control method for a vehicle includes: determining a crankshaft angle where a predetermined percentage of fuel injected into a cylinder was combusted during homogenous charge compression ignition (HCCI) operation of an engine; determining a valve closing timing adjustment for one of an intake valve and an exhaust valve of based on the crankshaft angle; generating a valve closing timing for the one of the intake valve and the exhaust valve of the cylinder based on the valve closing timing adjustment; and closing the one of the intake valve and the exhaust valve of the cylinder based on the valve closing timing.