Haltech IG5 - Manual (Page 66)

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** This configuration could also be used for waste-spark direct fire ignition.
B.2 Direct Fire Ignition
These are Ignition systems that do not distribute the spark through a distributor cap and rotor.
B.2.1 Ignition Outputs
There are two forms of Direct Fire Ignition. One has a separate coil per spark plug (usually
mounted on top of the plug) and the other uses a waste spark system described later in this
section. With either method each coil needs its own igniter- a single igniter can never be
used to fire two coils but an ignition output signal from the IG5 can input to two igniters.
With a waste spark arrangement, companion cylinders (cylinders with the same TDC but on
different strokes) receive a spark at the same time, one on the compression stroke and the
other on the exhaust stroke (the waste spark).
On a four cylinder engine using waste spark, two double ended coils are used and two ignition
outputs from the IG5 are needed. In this case Aux Out 1 (pin D) is used as the second ignition
output making it unavailable as an auxiliary output. Six cylinders with waste spark is similar
and requires 3 double ended coils and 3 ignition output signals. For this setup, Aux Out 1
(pin D) and Aux Out 2 (pin E) become ignition outputs and are unavailable as Auxiliary
Outputs. A V8 requires 4 double ended coils and 4 ignition outputs. For this setup, Aux Out
1 (pin D), Aux Out 2 (pin E) and Aux Out 3 (pin F) become ignition outputs and are
unavailable as Auxiliary Outputs. Refer to section B.2.2 for an example of coil connections.
1, 2 and 3 cylinder engines usually need 1, 2 and 3 ignition outputs respectively but a two
cylinder can use one ignition output to fire a double ended coil with a waste spark. This can
only be done if the engine is not an odd fire engine. Five cylinder engines can not run Direct
Fire as they can not use waste spark. There are not enough outputs to run Direct Fire on 10
and 12 cylinder engines.
B.2.2 Coil Setup
To give an example of how to match up the coils to the ignition outputs, we will use an
example of a V8 with an arbitrary firing order of : 1, 2, 7, 8, 4, 5, 6, 3. The companion
cylinders are the corresponding cylinders in each bank of 4.. Therefore the companion pairs
and their coil numbers would be - Coil One, cylinders 1 and 4; Coil Two, cylinders 2 and 5;
Coil Three, 7 and 6; Coil Four, 8 and 3. The diagram below (Figure 2.2) shows how the coils
would be connected.