VE and BLM cell edges

[Dave Zug]

----- Original Message -----
From: Bob Wooten <r71chevy at earthlink.net>
To: <gmecm at diy-efi.org>
Sent: Wednesday, January 17, 2001 6:31 PM
Subject: RE: VE and BLM cell edges


> I don't think that I am following completely.  Pardon the ignorance &
> indulge me for a minute.  this Util allows me to enter in the BLM value as
> I record them (diacom, data master etc) when i am running the car.  the
> Util will now say, if you are here (X) & you want to be here (128) then
you
> need to change the VE table by this (Y).  This makes sense to me & follows
> what Dan said two emails ago.
>

exactly.

yes its simple math, but to see it happen in front of you helps
understanding, and saves some time too. I had always thought in terms of the
VE's decimal number, not the calculated VE number though, but same idea....
I just did the simpler subtraction with the raw decimal insted of the div
128 thing. having done the work to show the cells that need changing when
BLM cell X is known helps alot I think. Its a core concept in P4 economy as
I see it and worth understanding. unfortunately you have to put up with *my*
understanding of it, unless someone else wants to correct / enhance the
conversation.

Not using a file from a scan tool, but using my eyeball, which has reviewed
the scanned data, and written down what the BLM's are. One thing about the
BLM's, (going a step farther in the details here) is that sometimes, when a
cell is recording, depending on if the RPM is near the top edge of the cell,
or near the bottom edge, the BLM number could be increasing in one
case(upper edge of the cell), and decreasing in another case (lower edge of
the cell). This makes for mistakes when looking ONLY at the final result of
the learning. you hafta look at the RPM and MAP during the corrections
within a cell to really nail the changes. I am toying with the idea of
changing the cell boundries to record in smaller increments, therefore
making changes easier to corolate.

> I think that the other thing you are saying (& here is where i am lost) is
> about the Cell edge values.  what I am reading here is that if the X axis
> of the line is 600 rpm, then the question is that line from 600 rpm to 699
> or is it from 501 to 600?.?.?.?.?  am I following or am i totally out to
> lunch?  & I am not following the last paragraph about the KPA @ all (brain
> dead).
>

the line is at 700, the way I read the coode (excluding hysteresis concept)
is that the borders are between 699-and-700 rpm,  1199-and-1200 etc, where
1200 is included in the UPPER cell. of coarse MAP calues make up the other
boundries.  I'm sorry its late.

> also I think that you are saying that you deciphered this information from
> the ANHT hac (that i have not gotten to yet).
>

not decyphered, just read it there ;-)  the only 'work' was in looking at
the assembly to see if it considered 700 as the last entry in one cell or
the first in the next higher cell

> If i am tracking right this sounds to me like a huge step towards science
&
> less of the "This feels like a touch here & a scosh there & a tad over @
> this part".

The part I was wanting to see comments (from the 'elite' ;-)  on was on the
subject of altering the cell border values to make things a little simpler
to tune. both using more convenient values as cell borders AND sliding the
borders ALL up and around, maybe even to 90 Kpa and 4000 RPM, with ONE cell
per VE table entry? not a new idea I bet, but maybe just not talked about.


>
> thanks
> BW
>

Hope I'm not cornfusing more than I am helping.. I tend to do that when I
get going.

>
>
> > [Original Message]
> > From: Dave Zug <dzug at delanet.com>
> > To: <gmecm at diy-efi.org>
> > Date: 1/17/01 6:00:42 PM
> > Subject: VE and BLM cell edges
> >
> > I have attempted to put BLM based adjustments in perspective with the
> layout
> > of the lower VE table in the '730 / 727, with the stock BLM cell edge
> > settings in mind.
> >
> > Here is a link to a snapshot I made of the tuning aide util I have been
> > messin with, I expanded it just a minute ago, to include the concept.
This
> > monster is growing as I enter new areas of actual tuning on my '730
swap.
> > Don't ask.. Its outta control... still not ready for beta testers
(  It
> > now will allow you to enter BLM recorded values and automatically adjust
> > your VE lower table. (not upper yet, later). I think if others are doing
> > similar packages that this is a useful addition, long as it is splained
> good
> > enough.
> >
> > http://www.delanet.com/~tgp/92Z28/pics/blcells.jpg
> >
> > Comments as to my interpretation of the cell edge values, which I am
> > confident of since I not only looked at the HAC BL cell map picture that
> > everyone has, but I also looked in the assembly code to see if the cells
> are
> > inclusive or exclusive, in relation to the cell edge values. they are
> > exclusive (ie 700 rpm belongs in the HIGHER cell, not the lower one.)
> >
> > This is not an original thought, but It seems to illustrate that if one
> were
> > to change the (Kpa) cell edge settings just a *bit*, that they would
> > corrolate more easily to edges in the lower VE table..no?
> >
> >
> >
> > ----- Original Message -----
> > From: Dan Townsend <xybertron at cox-internet.com>
> > To: <gmecm at diy-efi.org>
> > Sent: Wednesday, January 17, 2001 10:33 AM
> > Subject: Re: Questions from a newbie
> >
> >
> > > You take the BLM and divide it by 128.  If it is say 150 then you
> multiply
> > > the VE by 1.17 so the VE goes up because you are lean and need more
> fuel.
> > > If the BLM is 100 then you multiply the VE by 0.78125 since you are
> > running
> > > rich and want less fuel.  Following now?
> > >
> > > Dan
> > >
> > > ----- Original Message -----
> > > From: "Drew Skinner" <drew.skinner at lcra.org>
> > > To: <gmecm at diy-efi.org>
> > > Sent: Wednesday, January 17, 2001 8:20 AM
> > > Subject: Re: Questions from a newbie
> > >
> > >
> > > > Yeah, that's what got me thinking that I had a vacuum leak. My stock
> VE
> > > along with the cam netted some 4-5ms pulsewidths at idle, which had me
> > > changing fuel soaked plugs every week and not odriving the car for
fear
> of
> > > washing out rings and ther nasty things. After reading Bruce's tuning
> tips
> > > and prog101, I tried the old take %error in BLM and multiply VE and
that
> > > made everything much worse (~6-7ms PW) so I went the other way with
VE.
> > > >
> > > > My stock programming at 40-50KPA and 750 or so rpm had the ECM
looking
> > at
> > > VEs in the mid-high 60%, so I cut that back little by little and the
> idle
> > > PWs have come down to 2.0-2.4ms. I'm kinda at a loss, because this is
> > > obviously the opposite of what the ECM seems to want, but the engine
is
> > much
> > > happier. People (tuners) I have talked to with bigger cams and such
have
> > > mentioned that at low rpm (idle) larger cams with lots of overlap are
> less
> > > efficient and therefore require less fuel or VE in the table. Looking
at
> > > Bruce's VE table for the crossfire stuff I'm thinking I'm on the right
> > > track, I tried building a table closer to his and the car wouldn't
idle.
> > So
> > > I think I've found the two extremes and just need more iterations to
get
> > it
> > > right. As it is I haven't touched the upper VE table so the car
> hesitates
> > as
> > > it crosses the magical 1600rpm limit into the other VE table and PWs
> jump
> > up
> > > about 1.5ms or so.
> > > >
> > > > Does this logic sound completely screwy or does it seem like I'm
doing
> > > alright here?
> > > >
> > > > Drew (waiting for the king sized CSH)
> > > > '89 IROC
> > > >
> > > > >>> RRauscher at nni.com 01/16 6:51 PM >>>
> > > >
> > > > Drew,
> > > >
> > > > You mentioned trying to lean the VE table down, maybe a typo, but
high
> > > BLMs
> > > > would be adding fuel. A 40-45 Kpa idle sounds good, about 16" vac.
> With
> > a
> > > > 224 @ .050 & .465" lift, 108 LDA, runs about 50-55 Kpa in a 327.
> > > >
> > > > BobR.
> > >
> > >
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> >
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>
>
> --- Bob Wooten
> --- r71chevy at earthlink.net
> --- www.r71camaro.homestead.com
>
>
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