switching circuit for EFI sync trigger (LAC)

[auditude at neta.com]

Hello,

I'm waiting for some clarification that the LinkPlus standalone
engine management ecu I'm buying will be able to use the factory
MAC11 triggers without too many external "band-aids" or "patches".

It seems like it will, but it's possible that I would need to devise
something that would act as fast-acting, low-level switching circuit.

It would work by making sure the only sync signal sent to the ecu
is one that represents "two" signals being in phase.

Basically, it may be necessary for me to have a circuit that will be
normally open, and only close during those times that the single-
window distributor hall sensor window is in phase.

This would be the signal that controls whether the circuit is closed
or open.

What is being switched by this circuit, is the ignition timing
reference pin signal to the ecu.

If this was to work correctly, then the only time a signal would get
sent to the replacement ecu is when *both* signals are in phase.
When the #1 cylinder is at TDC (or before, whatever) on the
exhaust stroke, no signal would be sent to the ecu, even tho' the
flywheel pin is passing by the sensor.

This would be used as a sync signal, so the proper cylinders get
fired under a direct ignition concept, and the proper cylinders get
fuel injected under the sequential fuel injection concept.

It's entirely possible, and I'm hopeful, that they will be able to put
this functionality internal to the ecu.  If not, then it doesn't seem
that difficult from the outside either.  It's just a switching circuit.

Anyone have any comments on this?  For example, is there any
danger to the flywheel sensors, if their signal isn't applied to a
complete circuit?  Some thing's like to have their outputs go
through a certain resistance, which doesn't alway's include infinite
ones.

Thanks,

Ken