Haltech E6M - Manual (Page 119)

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B.3.3 Synchronising
To be able to synchronise the injectors with the motor, the E6H/E6M needs a
Synchronisation Event, usually in the form of a ‘Home’ Trigger to operate in sequential
mode. The Home trigger is separate from the main trigger and it tells the ECU that the next
injection is to be for channel 1. Each injection is calculated from a main trigger. The first
trigger after a Home trigger calculates injection for channel 1. Each main trigger after that
will sequence through the channels in the order mentioned earlier. i.e. the order will be
channels 1, 2, 5 and lastly 4 (if all four are used). If the Home trigger does not occur,
however, injections will continue, but injector synchronisation cannot be assured until the
home pulse is received again.
B.4 Multi-tooth Triggers
The E6H/E6M is capable of triggering from multi-tooth pickups, as used on a number of
production vehicles. The E6H/E6M employs software signal conditioning to convert the
multi-tooth trigger to standard form. This is done by counting teeth from a “synchronisation
event” (or Home signal), until a certain tooth is reached which corresponds to the engine
location specified as the Trigger Angle. The E6H/E6M then performs ignition (and possibly
injection) in the same fashion as the standard trigger.
After recognising the synchronisation event, the E6H/E6M will locate the first “standard”
engine trigger by the tooth indicated as Tooth Offset in the Ignition Set-up page. To find the
remaining “standard” engine triggers, the E6H/E6M counts a number of teeth equal to the
total teeth in one CAM revolution, divided by the number of cylinders.
For Example a 4-cylinder engine with a 24-tooth wheel on the cam and a corresponding home
would have the following setup values:
Trigger Angle: 65° (10° to 100° as required)
Trigger Type: Multi-tooth
Total Teeth: 24
Tooth Offset: 2 (1 to Total Teeth)
With these setup values, when the Home signal occurs the ECU will start counting the trigger
teeth (24-tooth wheel), when it reaches the tooth offset it will operate as a standard trigger.
The position of the remaining triggers is determined by taking the number of teeth in the
trigger wheel (24) divided by the number of cylinders (4). This number (6) is the number of
teeth that is counted between triggers.
In this case the triggers will occur at the following teeth: 2,8,14,20. Each trigger occurs 65°
(Trigger Angle) BTDC of the current cylinder and will perform ignition based on this angle.
Due to the high frequency of multi-tooth signals the maximum Rpm to which the ECU will
operate is 10,500 rpm.