Abstract: Method and apparatus for improving the operation of an internal combustion engine of the type having electromagnetically actuated gas exchange valves, in which the detachment time lag, the delay in release of the anchor plate from the electromagnet, is compensated-for in determining the proper time to shut-off current to the electromagnet. Embodiments include measuring individual electromagnet/anchor plate couple detachment times in the factory and presetting advances in the controller microprocessor, or contact sensing the total time of detachment plus flight during operation and compensating for the detachment time depending on calculated optimum time of shut-off, or engine operating conditions, including exhaust composition, cylinder pressure, ageing, temperature, knocking, engine output, and the like.