[Gmecm] BLM cell confusion

Fri Nov 11 16:16:05 UTC 2005

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
> (from
> > the "C/L INTEGRATOR WINDOW VALUE") before the BLM
> will
> > start to compensate, in which case, my idle cell
> INT
> > of 124 would be acceptable for no BLM
> compensation.
> >
> > Ryan
> >
> > --- Steve Ravet <Steve.Ravet at arm.com> wrote:
> >
> >> In general, "closed loop" allows the INT to vary
> to
> >> maintain stoich.
> >> "learn enable" allows INT changes to be
> accumulated
> >> in BLM.  Are you
> >> comparing driving around, where the BLMs move, to
> >> revving in neutral,
> >> where they don't?  Or what is the different
> >> condition that causes them
> >> to not move?  Either way, I don't know the answer
> to
> >> that one, why
> >> "learn enable" is enabled in one case, and
> disabled
> >> in another.  Anyone
> >> else got an idea?
> >>
> >> --steve
> >>
> >>> -----Original Message-----
> >>> From: gmecm-bounces at diy-efi.org
> >>> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of
> >> Ryan Hess
> >>> Sent: Thursday, November 10, 2005 2:17 PM
> >>> To: gmecm at diy-efi.org
> >>> Subject: RE: [Gmecm] BLM cell confusion
> >>>
> >>> Thanks Steve.
> >>>
> >>> My next question is what qualifiers there are
> that
> >>> enable the BLMs to move?  I can drive around and
> >> the
> >>> BLMs move just fine in response to the INT
> >> changing -
> >>> however - If I reset the PCM, start it up and
> >> bring it
> 
=== message truncated ===

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