US Patent 7819095 Electronic valve system

An internal combustion engine comprises a number of cylinders. The cylinders have electronically activated intake valves. Ignition coils for the cylinders are responsive to respective ignition signals such that charge accumulates in a coil for a cylinder when the ignition signal for the cylinder has a first state and then the charge causes ignition for the cylinder when the ignition signal for the cylinder changes to a second state. In response to detecting an intake valve fault in respect of a cylinder, the ignition signal for the cylinder is held in the first state for a number of cycles of the internal combustion engine, and is then switched to a second state to safely discharge the primary coil without combustion in the cylinder.