Injector Firing

[Shannen Durphey]

bruce plecan wrote:

> On a GM ECM, like what is used on the 87-89 camaros (TPI) they have the
> injectors wired into two groups of four.  Would that mean they alternate
> firing each group every 90 degrees?,  180 degrees?  360?.
>
> On the TBI's they fire in synch with the cylinders only at low fuel demand
> periods, right?.
>
> Do they do the same thing with the batch fired TPI's?.
>
> Thanks in advance
>   Bruce     nacelp at bright.net                    Cone shaped hat is really
> gettin
>
> comfortable, and the locals aren't
>                                                                  starring
> as much

  In synchronous mode, both TBI and batch fire tpi alternate banks, triggering
from the reference pulses.  So in crankshaft degrees, that would be 720/8=90
deg.  WOT, accel or decel, and cold enrichment operation are asynchronous, so
I'm told.

GM says I'm on a need to know basis, but they won't tell me what I need to
know.