VE and BLM cell edges

[timsiford at hushmail.com]

Dave,

Beautiful Idea!

Tim


At Wed, 17 Jan 2001 21:03:34 -0800, "Dave Zug" <dzug at delanet.com> wrote:

>
>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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