Ignition System - TFI: Operation: TFI-IV

The TFI-IV distributor uses a Hall Effect vane switch mechanism to induce primary voltage and to affect the discharge of the high secondary voltage. When a ferrous material passes into the Hall field, a magnetic flux is induced, charging the ignition coil primary circuit. As the material passes through and out of the field, the magnetic flux collapses, inducing the high secondary voltage. At this time, information on crankshaft position, engine load, and octane calibration is fed into the EEC-IV electronics for computation of the desired spark advance. See Figure.