[Gmecm] BLM cell confusion
Ryan Hess
rgmecm
Mon Nov 14 00:12:24 UTC 2005
Well according to Steve's previous post, it doesn't
increment linearly, but rather is like a
teeter-totter... The "plank" itself is always moving
to the rich or lean (like the integrator trying to
keep the engine stoich), and the pivot is moving to
bring everything into a long term balance (the BLM to
128)
It seems as though the increment of the BLM by one as
the INT hits it's limits is common in most other
applications (as you've seen with the 16 BLM cells),
but I have to say that the $a1 is different. It's
always trying to keep the int at 128 +/-4 (the INT
"action" window). It also appears that the INT takes
a much larger portion of the fueling equation.
That's how I observe it, anyways...
--- WopOnTour <wopontour at hotmail.com> wrote:
> 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
>
=== message truncated ===
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