Haltech IG5 - Manual (Page 83)

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C.3.1 Multitooth Triggers
The IG5 is capable of triggering from a multitooth pick up, as used on a number of production
vehicles. The IG5 employs software signal conditioning to convert the multi-tooth trigger to
standard trigger form. This is done by counting teeth from a synchronization event (until a
certain tooth is encountered which corresponds to the engine location specified as the Trigger
Angle. The IG5 then conducts ignition timing as normal.
After recognizing the synchronization event, the IG5 will locate the first “standard” engine
trigger by the tooth indicated as Tooth Offset in the Ignition Setup. To find the remaining
“standard” engine triggers, the IG5 counts a number teeth equal to the total teeth in one CAM
revolution.
C.3.2 Motronic Triggers
The motronic trigger is a type of multitooth trigger that incorporates a synchronisation event
in the trigger signal in the form of missing teeth. A typical motronic configuration is the 60-
tooth wheel with 2 teeth missing (it has 58 teeth and a space where two teeth have been
removed). The missing teeth cause a longer period between zero crossings or transitions
(depending on the pick-up used) which the ECU compares to the standard period and can then
identify the long period as the synchronization event. The diagram below shows the signals
the ECU will receive from the pick-up. The motronic trigger behaves in the same way as a
conventional multitooth trigger after the synchronisation event occurs.
Long Pulse due to
Missing Teeth
Signal generated by a reluctor pickup
Signal generated by a Hall effect pickup