BLM Cells for $88

[Bob Wooten]

I don't know if anyone wants to get into this but I am still REALLY foggy on
what a cell is.  I seem to recall that we had a short discussion on this,
but I still don't get it.  I do get the idea of the VE table having an X & Y
axis & that for some X & Y value there is going to be a VE number.
adjusting the VE number up or down to get the BLM (more on that in a minute)
to 128 is the trick.  I am picturing this as a 2D graph with RPM on one axis
& MAP on another.  Now I know that there is going to be a lot of these
tables as it is truly 3D, but a lot of 2D graphs work better in my brain
that one 3D graph.  this being said, & kept @ this simple level, how do the
cells work into it?  I can only imagine that for a graph that I am going to
group some of the MAPs & some of the RPMs together & call that a Block?

100
90
80
70
69
50
40__________
30          ]  <= One block?
20          ]
10          ]
   500, 1000, 2000, 3000, 4000, 5000, 6000, 7000

if I am not too far off here, then how does the BLM play into this?  I
thought that one BLM applied to every set of values in the table up & down,
but maybe this is the rub.  there is only one BLM for all the values w/in
that Block (logical no?).

Integrator.  the way that I correlate this is that I have two moving values
one w/in another.  the INT is in the BLM & the BLM is w/in this table.  if @
X & Y I have an IOT of Z (trying to keep it VERY simple, I know there is
more to it that that).  I check this to what I am commanding (14.7) & do
some math I find that I have to reduce (or raise) the IOT by some value. I
jack up the INT 1 number & check again.  if not close enough I do it again.
& I keep going until the INT hits a magic number (modifiable, right?) that
raises the BLM one number.  Now when I Multiply the BLM in it has a larger
affect in IOT than the INT does so I get a larger change to the IOT by the
changing of one BLM number compared to one INT number.  Assuming that the
MAP & RPM stay @ that point for the length of time that it takes me to type
this, I am going to jack up & down the INT & BLM until I get the commanded
AFR.  if this (the VE) is TOO far off both the INT & BLM are going to hit a
bottom (or top) & not be able to pull out any more IOT & the car is going to
just run rich.

Holly smokes, sorry again guys, I get going & before I know it I am off
topic. I hope that I am not too far of base.

BW




-----Original Message-----
From: owner-gmecm at diy-efi.org [mailto:owner-gmecm at diy-efi.org]On Behalf
Of rr
Sent: Monday, June 25, 2001 6:06 PM
To: gmecm at diy-efi.org
Subject: Re: BLM Cells for $88



At least some of the vehicles with 32 cells have 2 banks
of sixteen. One bank for normal use, the other when CCP
is active.

It might just be pointing out that high number of BLM cells
aren't really required?

BobR.

Squash wrote:

> Doesn't the BLM account for loss of engine efficiency?  Maybe efficiency
changes dramatically
> enough at different cell boundaries that it warrants having different
cells?  Why did GM love them
> so much?  Some TBI truck 350's have 32 cells, some 4.  Why the difference
on almost the same
> engine?
>
> Squash
>
> --- Scot Sealander <Sealand at clarityconnect.com> wrote:
> > "Gonyou, Jeremy (.)" wrote:
> >
> >
> > > >> Any reason the V6 stuff should only have 3 cells?
> > >
> > > >Any reason that it should have more?   ;-)
> > >
> > > Tuning?
> >
> > The BLM is used for correction of errant fueling, not tuning.  Correct
> > what's wrong first, then watch the BLM stay near the neutral value.
> >
> > Scot Sealander
>
> =====
> Trains, Trucks, and EFI at http://www.trailrunners4x4.org/users/realsquash
>

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