DFI, Batch Fire, and other myths

[Ward Spoonemore]

Roger
Most GM systems change the injection triggering during various phases of
operation. Most start out as A - B batch and fire  every 12.5 msec, or on
every other Distributor Reference Pulse.

Some start out in int 12 msec mode and switch to A - B, some never come out
of the 12 msec mode. These features are programmable.

Some ECM's have programmable saturated drivers or "peak and Hold" and some
have variable phasing like spark advance. I tried all of these features and
could not tell much difference.

Ward

-----Original Message-----
From: owner-diy_efi at efi332.eng.ohio-state.edu
[mailto:owner-diy_efi at efi332.eng.ohio-state.edu]On Behalf Of Roger
Heflin
Sent: Wednesday, January 20, 1999 9:52 AM
To: diy_efi at efi332.eng.ohio-state.edu
Subject: Re: DFI, Batch Fire, and other myths




On Wed, 20 Jan 1999, Andrew K. Mattei wrote:

> ECMnut at aol.com wrote:
> >
> > With the GM stuff, I believe most of the 8 cylinder applications
> > have injector circiuts A & B, and they alternate..
>
> I popped open my 165 ECM the other day ('89 TPI 350) to check this out,
> and though it has a left bank / right bank wiring, the traces are
> soldered together on the ECM board. So, in the case of the Chevy TPI
> 8-cylinder motor, they all fire together. :) (IIRC, only has one
> injector driver inside the ECM too.)
>

Looking in the 93 Z28 programming there appear to be two different
drivers.  They are using two different timer registers to time the
injector open time, which would lead me to believe that they are
handled differently.

				Roger