The Suppression of Electromagnetic Radiation from Motor Vehicles

A study by General Motors Corporation culminated in the development of an electromagnetic radiation suppression technique for car and truck ignition systems. The suppression technique described utilizes ignition resistor spark plugs, resistor ignition wire, and a widened distributor rotor gap. Test data is shown which indicates that significant electromagnetic radiation suppression is achieved with the technique, with no detrimental effects to engine performance, cold start, and exhaust emission controls. The low level of interference emitted with application of the technique is discussed in relation to the Society of Automotive Engineers Standard - “Measurement of Electromagnetic Radiation From Motor Vehicles (20 to 1000 MH_z)” - SAE J551a.