[Gmecm] Modify $8D to work on MPFI 3.1L DIS engine

[Robin Handley]

> > And a final note:  It is not desirable to offset a crank position
> > sensor
> > -60 deg to to allow an unmodified distributor calibration to be used
> > with the 7 notch DIS system.  During cranking and at any time the 5V
> > bypass line is held low, ignition pulses are delivered to the coils 60
> > deg. retarded from the reference pulse.  These pulses will be delivered
> > 60 deg ATDC with an offset crank sensor.  Starting will be extremely
> > difficult, requiring large amounts of fuel and quite possibly
> > backfiring
> > severely through the exhaust.  There is no need to alter the original
> > relationship between the crank sensor and notch position to convert
> > between DIS and distributor calibrations.

I hadn't thought about the cranking situation, but I'm now wondering how a
DIS based ignition system can actually get an engine to start (when the
'static' advance is so far away from something you'd want to use for
cranking). Does the DIS module do something clever here, that I'm missing?
(I'm used to dizzy triggering.) I've never found a clear description about
what a GM DIS module does.

Thanks,

Robin