eprom for 747

[Bruce Plecan]

> ok, so I'll take a look at the arpc bin, and if I'm not mistaking, that
> should be a $42?  Is there some way to change the rear end gear ratio in
the
> bin, or to even check to see if it is correct?   Because when using Tuner
> from tunercats, I can only edit fuel and timing related values.  And is
> there a way I can plug in data link with the ecm while driving, and even
> record?  I know there is diacom, but it is quite expensive, about 300$, is
> there any other programs, that would work pretty much the same and would
be
> a bit cheaper?

On the mask 42 there is no entry for final gear ratio.
The final gearing limits the way the engine can accept timing and fuel.

If we were to compare the same car/truck/van, with everthing identical but
the finally gearing, a few thing would pop into view.  Just for a
comparision, I'll be using 4.11s as a high gear set, and 2.74s as low.
  The higher gear setted motor, would get more AE (accelleration
enrichment), and the timing would drop off slower leaving cruise and going
to WOT
  the cruise VE might be a little lower with the Higher gears also.
  The higher rear gears, pose less of a load, so the engine engine can
change speed faster, and that must be accounted for or performance and
drivibility will suffer.
   Also to, the limits for knock retard might be set differently.
   Then on really vastly different combs the IAC limits may change.
This is why I suggest to start with an oem chip similiarly as possible to
what you're running.
   Couple weeks ago I reprinted the timing table out of my XFire,  that was
a 355 cammed SBC in a car carrying 3.23s, and weights 3K lbs.  You notice a
whole area where the timing dropped to -6d.  That was because, it would just
light the tires so hard as to be useless to run any more then that.
   Which brings up, the flash speed of the converter, or how fast the clutch
is used,  it's is conceivable, that you might even have to consider some
clutch slippage in the tuning of a real hot car.
   Then as you get to other ecms they need more gear information.
Now that I think about it, there might be some gearing issues, in a 42 but
**not serious** ones.
For a full hac of the 42 try finding the ecmguys page,  there is a copy
there
HTH
Bruce


Thanks
>
>     Math B
>     fireb76 at videotron.ca
>
> ----- Original Message -----
> From: "Bruce Plecan" <nacelp at bright.net>
> To: <gmecm at diy-efi.org>
> Sent: Thursday, November 23, 2000 10:34 PM
> Subject: Re: eprom for 747
>
>
> >
> >
> > >     I'm real new here, and I have two small and easy questions. First,
> if
> > I
> > > want to buy some extra eprom to write on for a 747 ecm, what would be
> the
> > > size of it ( i guess pins and kb wise), I mean model maybe.
> >
> > 2732As, are what you want.
> >
> > >     and for the other one, well I tried to use the winbin program,
where
> > it
> > > ask for both a .ecu and .bin file to start, i tried several
combination
> of
> > > 747 files, but without any sucess. Anyone can help me out.  I also
tried
> > > different programs, but the only thing that seem that can be edited
are
> > the
> > > fuel and timing related tables.  But how then I can change some other
> > basic
> > > specs, like rear end ratio, automatic -> manual, ... or is it even
> > possible,
> > > or would it make a difference.
> >
> > manual to auto are different strategies for some areas of the program,
> much
> > much easier to start with something close to what you have,
> >
> > >  The problem is that I can't seem to find a
> > > bin for a 305 tbi manual trans K1500 pickup.  Could I use a file for a
> > 5.7L
> > > and adjust the fuel and timing to a 5.0L?
> >
> > Got to the Home Page the GMECM then ecms by number 1227747 then get
> > ARPC
> > Bruce
> > >
> > >     Math Blais
> > >     fireb76 at videotron.ca
> > >
> >
>
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