## ELECTRONIC IGNITION

### Description and Operation

In 1975, in order to comply with California's tougher emission laws, Datsun/Nissan introduced electronic ignition systems for all models sold in that state. Since that time, the Datsun/Nissan electronic ignition system has undergone a metamorphosis from a standard transistorized circuit to an Integrated Circuit system (IC), and later to the special dual spark plug system used with some models.

The electronic ignition system differs from the conventional breaker points system in form only. Its function is exactly the same: to supply a spark to the spark plugs at precisely the right moment to ignite the compressed gas in the cylinders and create mechanical movement.

NOTE: On some late model vehicles a crankangle sensor mounted in the distributor is the basic component of the entire E.C.C.S. (Electronic Concentrated Control System). There are no adjustments necessary.

Located in the distributor, in addition to the normal rotor cap, is a spoked rotor (reluctor) which fits on the distributor shaft where the breaker points cam is found on non-electronic ignitions. The rotor (reluctor) revolves with the top rotor cap and, as it passes a pickup coil or stator inside the distributor body, breaks a high flux phase which occurs while the space between the reluctor spokes passes the pickup coil or stator. This allows current to flow to the pickup coil or IC ignition unit. Primary ignition current is then cut off by the electronic ignition unit, allowing the magnetic field in the ignition coil to collapse, creating the spark which the distributor passes on to the spark plug.

The dual spark plug ignition system uses two ignition coils and each cylinder has two spark plugs which fire simultaneously. In this manner the engine is able to consume large quantities of recirculated exhaust gas which would cause a single spark plug cylinder to misfire and idle roughly.

Some later models use a crankangle sensor. This sensor monitors engine speed and piston position and sends to the computer signals on which the controls of the fuel injection, ignition timing and other functions are based. No maintenance is required but inspect and replace, if necessary, the spark plug wires, rotor head and the distributor cap every 30,000 miles or 24 months.

Service on electronic ignition systems consist of inspection of the distributor cap, rotor and ignition wires replacing them when necessary. Check the ignition wires for cracking of exterior insulation and for proper fit on the distributor cap and spark plugs. These parts can be expected to last for at least 40,000 miles but you should inspect these parts every 2 years or 30,000 miles. In addition, the reluctor air gap should be checked periodically if the system has no crankangle sensor.

NOTE: All models without a crankangle sensor type ignition system use IC ignition unit and no pickup coil. Measure the air gap between the reluctor and stator assembly. If not within specifications (0.300.50mm), loosen stator retaining screws and adjust. Refer to the necessary service procedure.