Fiat 1998 Marea Weekend, Service Manual

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Marea-Marea Weekend®
lev
Engine
1998 range
Fuel system
10.
When the voltage required for triggering an arc between the spark plug electrodes is examined, we note
that voltage is high in the cylinder undergoing compression (about 10kV) while it is reduced (about
5kV) in the cylinder undergoing exhaust.
High tension distribution is static, i.e. takes place without a rotary brush and cap. This system effectively
does away with a distributor. This gives the system a considerable advantage because it is known that
brush and cap insulation properties play an important role. Any loss of insulation to earth may impair ig-
nition: particularly during winter or periods of heavy rain.
The spark plugs of cylinders 1 -4 and 2-3 are connected directly (in pairs) by means of high tension
leads to coil secondary winding terminals and may be considered to be connected in series, because the
cylinder head joins them all. This solution is also known as a "lost spark" system because the energy
built up by the coil discharges almost exclusively on the electrodes of the spark plug located in the cylin-
der under compression to allow mixture ignition. The other spark is obviously unused because the cylin-
der does not contain mixture for ignition - solely exhaust gas ready for venting.
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1. Rpm and TDC sensor
2. Crankshaft pulley with phonic wheel
3. Battery
4. Ignition switch
5. Spark plugs
6. Ignition coils
7. Injection system relay
8. Electronic injection-ignition control unit
9. Injection-ignition system fuse
10. Injection-ignition control unit fuse
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