A method for a hydrogen fueled internal combustion engine to reduce backfiring, pre-ignition, and/or backflash, the engine also including a combustion chamber, an intake manifold, an exhaust manifold, at least one intake valve, at least one exhaust valve, a hydrogen injector, a compression device, and a variable valve timing system coupled to the intake valves. The method comprises compressing air using the compression device; injecting hydrogen and mixing at least said hydrogen with air discharged from the compression device; and opening the intake valve to induct at least air into the combustion chamber, wherein the intake valve opening time varies with an operating condition.