VE and BLM cell edges

[Dave Zug]

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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