[Gmecm] BLM cell confusion
Ryan Hess
rgmecm
Sun Nov 13 17:52:52 UTC 2005
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 ===
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