Haltech E6M - Manual (Page 145)

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E.4 Synchronisation Events
Synchronisation Events (Sync Events) are required for sequential and direct fire systems. The
Sync Event gives the ECU in indication of the engines position. The most common form of
Sync Event is a Home Trigger. Other Sync Events are the missing teeth on multitooth
triggers. A Home Trigger is usually a separate trigger from the main trigger, but some special
trigger sensors, such as the Haltech Hall Effect Sensor, can generate both signals from the one
sensor.
For a direct fire system the home trigger tells the ECU that the next trigger is for coil one
(which is usually connected to cylinder one). The ECU then cycles through its ignition
outputs until it expects a Home trigger again. If it receives a Home it will cycle again. If it
does not receive a Home before the next trigger, it will not output a spark until the Home is
received.
Home triggers for the E6H/E6M do not need to be accurately timed. All it does is tell the
ECU that the next main trigger is significant. Usually, but not necessarily, the significance is
that the next main trigger is for cylinder one. Therefore, the Home trigger must occur before
the main trigger for cylinder one and after the main trigger preceding the cylinder one trigger.
(See Figure 6). The Home trigger should not occur at the same time as any other trigger.
Check that the trigger and Home Edges are set correctly.
Figure 6. Home Trigger position on a cam angle sensor for 4 cylinder with a home trigger occurring every
cam revolution.