Haltech E6A - Manual (Page 113)

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Figure E.2
In the previous examples the trigger edge has been shown as the first edge of the trigger pulse.
The trigger does not necessarily have to be the first edge of the trigger pulse. Consider the
example shown in figure E.3. In some trigger devices the pulse given for cylinder one would be
a different width than the pulses given for all the other cylinders. If the first, in this case, rising
edges were used as the trigger edge then there would be a variation of 20° between the trigger
for cylinder one and all other cylinders. This would lead to cylinder one being 20° more
advanced than all the other cylinders and obviously this would be unacceptable. The answer in
this case would be to set the trigger point so that it is at a falling edge and to have the trigger
degrees set to 60° BTDC.
Figure E.3
E.2 Trigger Devices
The output of Hall Effect or Optical sensors could normally be connected directly to the input
trigger pin of the E6A ECU. Many distributors uses in original equipment manufacturer’s
computer controlled ignition systems would be fitted with Hall / Optical triggers. The internal
structure of such distributors is usually configured so that a chopper wheel attached to the
distributor shaft passes through a gap in the sensor. These devices require three connections :
Power (normally +12v)
Ground, and
Trigger signal output.
Assuming that the timing edges conform to the details set out above, a distributor such as this
would connect directly into the E6A ECU. Often these distributors have a rising edge trigger
at 70° BTDC.