Re: Editing proms (editorial)

["Kevin R" <KEReyn@gte.net>]

Ludis,
I wasn't sure on how you were saying the ECM corrected for the AFR if the
constants weren't set for the combo, i.e. using a 5.7 chip for a 383 with
90lb injectors.
What you're saying is that it doesn't reevaluate the constant, but that the
AFR settings for PE and WOT etc check the BLM settings and adjust
accordingly !?? With in it's range of course.
I didn't realize that anything else used the BLMs for their calculations. Is
this true for most/all fuel parameters?

Thanks,
Kevin R


----- Original Message -----
From: "Ludis Langens" <ludis@cruzers.com>
To: <gmecm@diy-efi.org>
Sent: Friday, August 18, 2000 5:28 AM
Subject: Re: Editing proms (editorial)


> Kevin R wrote:
> >
> > Now for my continued learning, are you (Ludis) saying that the ECM(in my
> > case a 747) will adjust the constant somehow thus making the numbers
more
> > accurate?
> > Example:
> > Say I have a 350 with 70lb injectors and the constant is set for this
> > injector/CI combo. Then if I bump up the FP to increase the injector
output,
> > thus throwing off the VE and AFR numbers in the ECM. Will it (the
ECM)then
> > see that the command AFR is off and make an adjustment bringing
everything
> > back to close to real numbers? I was under the assumption (never assume
I
> > know) that it would just move the BLM and call it a day leaving the WOT,
PE
> > etc AFR numbers off. Since in this case the constant (if not adjusted)
would
> > be set for 70lb while the injectors would be actually putting out say
> > 85-90lb making the AFR richer than the bin called for.
>
> When the ECM goes closed loop, it'll see that the VE numbers are wrong.
> It'll (try to) adjust the BLMs to bring the engine back to stoich.  In
> other words, while the requested AFR is 14.7:1, the ECM will adjust the
> BLMs such that the engine really is running at 14.7:1.
>
> If you then go to PE mode (ie, request an AFR richer than 14.7:1), the
> ECM will do some math and end up running the engine very close to the
> requested AFR.  (There are conditions under which it will ignore the
> learned BLMs.  Or the BLMs may poorly map the conditions experienced
> during PE.  Either will throw the actual AFR off from what the ECM
> thinks it is generating.)
>
> I don't quite understand where your confusion is.  The ECM never
> "changes" the injector constant or the numbers is uses for AFR.
>
> --
> Ludis Langens                               ludis (at) cruzers (dot) com
> Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/
>
>
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