BLM Cells for $88

[Len Sabatine]

    Ok ,for an example , lets say your working with an 8262. While 
operating the Ecm
    is using cell block 14 [ 10 cells @ 50 - 55 Map and 12 - 1600 Rpm]. 
This is the VE
    region in use at the particular speed , load , rpm requirement. ECM 
needs to use
    a block of cells to balance out the variables with which the Vehicle 
operates.
    Otherwise , the Ecm would be constantly "hunting" rather than 
"focusing" on the
    fueling needed at that time. Most Editors display the VE Tables in a 
spreadsheet
    style format , which is much easier to work with. Take a spin and log 
INT and Cell
    number to know where fueling is being looked up under those conditions.

    Running too fat in a particular Cell Block , subtract Ve #. The 
opposite is true for
    lean condition [ high INT value ]. This is simplistic explanation , 
Does this help you ?
    Len

>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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