Haltech E6X Manual DOS Version User Manual
Page 124
E6X Manual
124
The trigger signal consists of the same number of pulses as the engine has cylinders. The
beginnings of the pulses (rising edge) are evenly spaced, but the ends of the pulses (falling
edges) are not evenly spaced. The differing pulse widths enables the ECU to synchronise
engine position with ignition and fuel timing, the ECU does this by counting the number of
home pulses that occur during the trigger pulse.
There are a number of different trigger window patterns, two common patterns are described
below:
Pattern 1
The first pattern has trigger windows sizes that are related to the cylinder number which they
precede and can be calculated using the following equation:
4
1))
-
Number
(Cylinder
-
cylinders
of
(Number
Pulses
of
Number
×
=
For Example: A 4-cylinder engine that is to be synchronised before cylinder 2 would have a
trigger window as follows:
12
4
1))
-
(2
-
(4
Pulses
of
Number
=
×
=
Cyl. 4 Window
Cyl. 6 Window
Cyl. 1 Window
6-Cylinder Nissan Trigger 1
Pattern 2
The second pattern is similar to the first but instead of having different size trigger windows
for each cylinder it has pairs of trigger windows matching the two cylinders that are
approaching TDC together on opposite strokes (i.e. compression-combustion and exhaust-
induction). The first pair is not a true pair; the two windows differ by a number of home
pulses in size, all successive pairs are identical in trigger window size so a 4-cylinder engine
has one odd pair and one true pair.