[Gmecm] Big cap HEI on 7747

[Mike V]

At 07:26 PM 6/22/2006 +0100, you wrote:
>"In batch PFI/TPI (at least for 1226870), hardware in the ECM divides the
>distributor reference pulses by 2 (L4), 3 (V6), or 4 (V8).  The injector
>firing is triggered by this divided signal.  The result is one firing
>per cam revolution, aka two firings per intake valve opening."
>
>This doesn't sound right to me. IME with L4 engines, the distributor is
>driven directly off the cam shaft and so rotates once for every cam
>rotations. The distributor has 4 trigger points (whether it's Hall or
>reluctor). So, one rev of the cam shaft generates 4 pulses. The cam shaft
>rotates once for a complete engine cycle - which includes each cylinder
>firing once (hence the 4 trigger points per cam revolution). Therefore, if
>the ECM (or, pedantically, the software :-) divides the distributor pulses
>by 2, then the result will be 2 per cam revolution. If the injectors are all
>triggered together by this divided signal then surely that means that they
>will fire TWICE per cam revolution (not once).
His sentence makes sense if you substitute the word "crank" in place
of "cam".