Fiat Bravo Service Manual page 423

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When examining the voltages required for the spark between the plug electrodes, it may be noted that in

the cylinder at the compression stroke, this voltage is high (over 10kV) while in the cylinder in the ex-

haust stroke the voltage is l o w (about 5kV).

The high voltage distribution is static, i.e. characterized by the absence of a rotor arm and cap, and thus

the distributor is in effect eliminated. This offers a considerable advantage to the system as it is k n o w n

that the insulation characteristics of the rotor arm and cap play a fundamental role; any dispersion of i n -

sulation towards earth can be detrimental t o ignition, especially during winter or in heavy rain.

The spark plugs of cylinders 1 - 4 and 2-3 are connected directly (two by t w o ) by high tension cables t o

the terminals of the coil's secondary winding, and their connection may be considered t o be serial as the

cylinder head joins them. This solution is also called "lost spark" as the energy accumulated by the coil

will be almbsTexclusively discharged oh the electrodes of the spark plug located in the cylinder under

compression, allowing the mixture to be ignited. The other spark is naturally not used, as there is no mix-

ture t o be ignited in the cylinder, only an environment of used gas at the exhaust stage.

r & , 5 A | - i

1. Rpm and TDC sensor

2. Crankshaft pulley with phonic wheel

4. Ignition switch

5. Spark plugs

6. Ignition coils

7. Fuel injection relay

8. Fuel injection-ignition electronic control

9. Fuel injection-ignition system fuse

10. Fuse protecting fuel

control unit

injection-ignition