BOSCH Hall Effect Electronic Ignition: Description
NOTE:
Federal Vanagon models use a Bosch single breaker distributor. The Audi Quattro uses the Bosch-Hitachi Digital Timing Control system. See appropriate article in the Computerized Engine Control section.
The Bosch Hall Effect electronic ignition system consists of a breakerless Hall Effect distributor, a Hall (ignition) control unit, ignition coil, ignition switch, and battery.
Closely allied with the ignition system on Audi, Porsche and Volkswagen models is an idle stabilizer, a solid state control unit located between the Hall (ignition) control unit and the distributor's Hall generator.
It replaces the distributor in sending signals to the ignition control unit when engine speeds fall below 940 RPM.
NOTE:
Saab models do not use an idle stabilizer. On Audi 4000 (with 5-cylinder engines) and 5000 models, a gray-colored impedance transformer is installed in place of the idle stabilizer. Its purpose is to prevent interference and protect instruments from excessive voltage.
The Hall Effect distributor has normal centrifugal and vacuum advance mechanisms. See Figure and Figure.