G4 Wiring and Installation Manual34
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and coil is shown below.
PICTURE - figure 8.3
Wiring of igniter and coil
The igniter is basically a solid-state switch, which may also limit the coil current to a
predetermined value. This limiting feature eliminates coil ballast resistors and provides
protection of the coils if the dwell time (time the coil is charged for) is set too long. Over
voltage clamping is incorporated to prevent damage to the igniter should a high-tension lead
become disconnected or similar.
Each one of the ignition drives may be used to switch a separate channel on an igniter.
Each channel on the igniter is used to switch an ignition coil. The following examples show
the requirements for some common ignition configurations:
Example - 4 cylinder engine with direct spark
· Four ignition drives must be used
· A four channel igniter (or 2 x 2 channel igniter's) must be used
· Four Single Post Coils must be used
Example - 4 cylinder engine with wasted spark
· Only two ignition drives are used (Ign. 1 and Ign. 2)
· One two channel igniter must be used
· Two Dual Post Coils must be used
Example - Engine with single distributor ignition
· Only one ignition drive is used (Ign. 1)
· A single channel igniter must be used
· One Single Post Coil must be used
Conventional igniters begin to charge the coil when their input is high. Spark occurs when
the input goes low. This is known as a Rising 'Dwell Edge'. Some factory igniters (eg some
Ford and Honda), MSD ignitions and some other units work in the opposite sense. The coil
begins to charge when the input signal goes low while spark occurs on the transition from
low to high. In these cases, a Falling 'Dwell Edge' must be selected in PCLink Tuning
Software.
Always mount igniter(s) in the engine bay as close to the ignition coil(s) as possible. This
helps to minimize the length of high current wiring between the igniter(s) and coil(s).
NEVER mount the igniter(s) on or near to the G4 ECU
Avoid areas of high temperature such as exhausts, turbo chargers and radiators since the
igniter itself will generate heat at high power. If vibration levels will be excessively high,
some form of soft or rubber mounting is advisable to prevent component and wiring fatigue.
High current ignition wiring should NOT be run along side other ECU wiring. Separate high
current ignition wiring into its own loom running directly to the coils.
8.2.2 Coil Requirements
The coil required for a particular application will depend largely on the method used to drive
the coil and the spark energy requirements. Consult the igniter manufacturer for a
recommended coil for use with a particular igniter.
The required Dwell Time will be entirely dependent on the coils inductance. Dwell time
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