Mazda 323/626/929/GLC/MX-6/RX-7 1978-1989

Description and Operation

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Most of the vehicles covered by this information use an electronic ignition system in place of the old breaker point system. The electronic systems used on vehicles covered by this information come in two basic forms: with and without distributor. Although, just like the breaker point systems, the distributors used on rotary engines is significantly different from those found on piston engines.

The electronic distributor systems replace the contact points (used in traditional breaker point systems) with an electromagnetic generator. The generator consists, in part, of a rotating pole piece (reluctor or signal rotor) on the distributor shaft and a stationary pickup coil. As the pole piece passes the pickup coil, current is generated, much as in the car's main electrical system alternator. Spikes of current are produced as each of the four corners on the pole piece pass the pickup coil and operate transistors in the igniter mounted on the coil. This provides the switching actions ordinarily handled by the contact points, but without the arcing and stress of opening and closing associated with point operation.

All 1980-85 RX-7 models are equipped with electronic distributor ignition systems which replace the conventional breaker points and condensers used in the 1979 RX-7. In place of the two sets of breaker points used in 1979 models, two pickup coils (leading and trailing) are found inside the distributor on 1980-85 models. In place of the rubbing block cam found on the distributor shaft of point-equipped models, is a four-spoked wheel called a signal rotor. Other parts of the system include the igniter, the two ignition coils and all attaching wires. When each of the spokes on the signal rotor passes in front of one of the pickup coils, it creates a signal. The pickup coil then sends this signal to the igniter and the appropriate ignition coil. This signal causes the magnetic field in the coil to collapse, creating the spark which the distributor cap passes on to the spark plug. As with the 1979 breaker point system, there is a leading and a trailing spark plug. The leading plug fires first, followed (after about 10 degrees of distributor shaft rotation) by the trailing plug, which ignites any remaining air/fuel mixture in the combustion chamber.

The 1986-89 RX-7 models utilize a distributorless ignition system, in which the distributor has been eliminated in favor of a crank angle sensor (for crankshaft position information) and ignition coils which fire the spark plugs directly from their own towers. For more information on the crank angle sensor, please refer to Engine & Engine Overhaul of this repair guide.

 
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