[Gmecm] BLM cell confusion

Sun Nov 13 23:40:02 UTC 2005

Well first you need to operate it so it's IN cell 2 (In gear with some RPM 
above idle??)
In any cell, as integrator climbs small amounts of  injector pulse 
width/delivery (bpw x 1.001?) are occurring. When integrator hits it's high 
clamp point (eg 138) it will increment BLM +1 and reset integrator to 128. 
This would result in an increase from the base delivered fuel or base pulse 
width x 1.01 This cycle will continue if the O2 feedback continues to show 
leaner than stoich. So in your example if BLM in any cell achieved 128+5 
(133) when it finally achieved a stoich ratio this would equate (depending 
on calibration) to say bpw x 1.05 This value will then remain "stored" in 
this cell so that next time the vehicle is at the same load (same cell) it 
will commence immediately with a 1.05 factor. Of course the opposite occurs 
if O2 feedback is indicating RICHER than stoich.
Well that's the way I understand it anyway
Hope it helps
WopOnTour

----- Original Message ----- 
From: "Ryan Hess" <rgmecm at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: Sunday, November 13, 2005 10:52 AM
Subject: Re: [Gmecm] BLM cell confusion

> Any other ideas about getting cell 2 to learn?  I'm
> really stumped here.
>
> Or - maybe you can explain the relationship between
> INT and BLM?  I think I read somewhere that one INT
> step is 1/2 a BLM step?  So could I say an INT of 138
> would correspond to the current BLM + 5?
>
> Ryan
>
>
> --- Ryan Hess <rgmecm at yahoo.com> wrote:
>
>> That helps immensely, Gary, thanks!
>>
>> Since all the other conditions are being met, I'll
>> just have to assume it's my BPW that isn't above
>> 1.08.
>>  It's hard to tell when the ALDL data only puts out
>> integers...
>>
>> But in starting to tune the main VE table, I guess I
>> would want cell 2 'learn enabled' while I hold the
>> engine at some specified RPM, and "anchor" the VE
>> table at that point with a BLM of 128 by changing
>> the
>> BPC vs EGR constant, then go open loop and start
>> tuning the VE via wideband.
>>
>> I guess the problem is in enabling block learn.  The
>> BPW you mentioned of 1.08 is in the low hysteresis
>> constant...  I don't understand hysteresis to begin
>> with, but I assume if I changed it to 0.7, I would
>> want to change the high hysteresis value to around
>> 1...
>>
>> Ryan
>>
>>
>> --- Gary Evans <gary at garyandliz.com> wrote:
>>
>> > The $A1 code uses 3 BLM cells:
>> >
>> > Cell 0 = idle
>> > Cell 1 = part-throttle
>> > Cell 2 = "overrun" aka no load
>> >
>> > As you have discovered, cell 2 is entered on the
>> > conditions of high
>> > (ish) RPM and low map, such as coasting with the
>> > throttle closed. I'm
>> > not sure what the point of the cell is other than
>> > for emissions
>> > purposes.
>> >
>> >  From the ARUR bin, the vales required to enter
>> Cell
>> > 2 are:
>> >
>> > Map less than 32 kPa
>> > BPW less than 1.95 mSec
>> >
>> > There are also a number of conditions that must be
>> > met for block
>> > learn to be enabled. MAP, BPW and RPM must all be
>> in
>> > a certain range.
>> > For the ARUR bin, the conditions are:
>> >
>> > Closed loop conditions met (Coolant temp up,
>> engine
>> > run time met, no
>> > fault codes, o2 sensor ready)
>> > Charcoal canister not purging.
>> > RPM between 400 and 6375
>> > MAP above 22 kPa
>> > BPW above 1.08
>> >
>> > If you are just revving the car in neutral, it is
>> > likely that one of
>> > the conditions is not being met. The time it takes
>> > for the BLM to
>> > update is also dependent on how far the INT is
>> from
>> > 128. The table
>> > looks like this:
>> >
>> > ###########################################
>> > #     F58 TABLE                           #
>> > #    BLOCK LEARN DELAY TIME INTERVAL      #
>> > #       VS. DELTA BETWEEN INT AND 128     #
>> > #   TABLE VALUE = SEC*20                  #
>> > ###########################################
>> > 8997        52     82 F58A           4.1 SEC
>>
>> > 0    INT-DELTA
>> > 8998        4C     76                3.8 SEC
>>
>> > 2
>> > 8999        3C     60                  3 SEC
>>
>> > 4
>> > 899A        32     50                2.5 SEC
>>
>> > 6
>> > 899B        2C     44                2.2 SEC
>>
>> > 8
>> > 899C        28     40                  2 SEC
>> > 10
>> > 899D        24     36                1.8 SEC
>> > 12
>> > 899E        20     32                1.6 SEC
>> > 14
>> > 899F        1C     28                1.4 SEC
>> > 16
>> > 89A0        18     24                1.2 SEC
>> > 18
>> > 89A1        14     20                  1 SEC
>> > 20
>> > 89A2        14     20                  1 SEC
>> > 22
>> > 89A3        14     20                  1 SEC
>> > 24
>> > 89A4        14     20                  1 SEC
>> > 26
>> > 89A5        14     20                  1 SEC
>> > 28
>> > 89A6        14     20                  1 SEC
>> > 30
>> > 89A7        14     20                  1 SEC
>> > 32
>> >
>> > So, a delta of 4 (INT at 124, for example) will
>> not
>> > start to move the
>> > BLM for at least 3 seconds.
>> >
>> > Each calibration will be a little different, but
>> > that is the gist of
>> > it. With so few cells, the BLMs will naturally
>> vary
>> > with driving
>> > conditions. If it varies a lot then there is room
>> > for improvement in
>> > the tuning of your VE tables. In a perfect world,
>> > the VE tables would
>> > perfectly represent the exact airflow for every
>> > condition. In the
>> > real world it's never gonna happen, so don't spend
>> > too much time
>> > chasing "perfect" 128 values. Even filling your
>> car
>> > with a different
>> > grade of gas can throw the values by a few, so a
>> BLM
>> > of 124 is
>> > perfectly acceptable, nay, even excellent.
>> >
>> > If you do not have it already, I highly recommend
>> > getting ahold of
>> > the $a1 disassembly file and making an effort to
>> > understand the
>> > things the computer is looking for in its
>> operation.
>> > Even if you do
>> > not understand all the computer language stuff,
>> just
>> > looking at the
>> > tables and comments can be very enlightening.
>> >
>> >
>> > -Gary
>> >
>> >
>> > On Nov 10, 2005, at 8:07 PM, Ryan Hess wrote:
>> >
>> > > Yes, exactly.  Entering cell 2 (by reving in
>> > neutral)
>> > > swings the INT to 137-ish, but the cell 2 BLM
>> > doesn't
>> > > change off 122.  I don't know if learn enable
>> has
>> > some
>> > > kind of qualifier that I'm not meeting in
>> neutral
>> > > (MPH? MAP? BPW?) or what, but cell 2 appears to
>> be
>> > the
>> > > only one that doesn't move.
>> > >
>> > > An interesting side note is that my BLM data
>> > varies
>> > > widely depending on the driving that I do.  But
>> -
>> > I
>> > > guess that's to be expected if the $a1 truly
>> does
>> > use
>> > > only 2 BLM cells (idle and off idle).  I don't
>> > know
>> > > that it does.  I can say that BLM cell 2 does
>> > appear
>> > > to be calculated from the cell 0 (idle) and cell
>> 1
>> > > (seems to be a changing TPS).  I never see cell
>> 2
>> > > actually change, it only changes when you're in
>> > other
>> > > cells... "behind closed doors" so to speak.
>> > >
>> > > Now, from what I have seen in my data logs, it
>> > appears
>> > > as though the INT has to be off from 128 by 4
>>
> === message truncated ===
>
>
>
>
> __________________________________
> Yahoo! FareChase: Search multiple travel sites in one click.
> http://farechase.yahoo.com
> _______________________________________________
> Gmecm mailing list
> Gmecm at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/gmecm
> 