When a spark plug is fired with forward polarity, current flows from the centera#39;s positive to the sidea#39;s negative electrode. (General Motors) ... Inside the distributor is the familiar magnetic pulse generator, but TFI-I is a variable dwell system that operates without a ballast resistor. ... A revised TFT ignition system appeared in 1983 as part of Forda#39;s fourth generation of electronic engine controls (EEC-IV). Calledanbsp;...