[Gmecm] BLM cell confusion

[Ryan Hess]

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
up to temp, and enter cell 2 (high RPM, about 1500 it
seems) you can see the INT rise quickly to 138, but
the BLM stays stuck on it's default 122.  Cell 0
(closed throttle/idle) also stays on it's default of
128, althoug the INT is 124, so that probably isn't as
big of a deal..

Ryan


--- Steve Ravet <Steve.Ravet at arm.com> wrote:

>  
> 
> > -----Original Message-----
> > From: gmecm-bounces at diy-efi.org 
> > [mailto:gmecm-bounces at diy-efi.org] On Behalf Of
> Ryan Hess
> > Sent: Sunday, October 30, 2005 12:37 PM
> > To: gmecm at diy-efi.org
> > Subject: [Gmecm] BLM cell confusion
> > 
> > Hi everyone,
> > 
> > I'm working with the $A1 code, and have been
> slowly
> > conquering a steep learning curve.  I'm still
> greatly
> > confused about the BLM cells.  How they work, and
> the
> > differences between cell 0, 1 and 2...  For
> instance,
> > I've gathered cell 0 appears to be closed throttle
> > idle conditions.  The others I don't know. 
> Secondly,
> > how do the BLM cells increment?  They follow the
> INT,
> > but how?  'preciate it,
> > 
> > 
> 
> The INT is part of the feedback loop and so
> constantly moves up and down
> as the ECM maintains stoich.  There is no "history"
> with INT, it just
> changes to whatever value is required.  The BLM
> provides the history.
> If the INT is consistently high or low for a period
> of time then the BLM
> will start to move in that direction.  Both INT and
> BLM are part of the
> fueling equation, so as BLM starts to move INT will
> tend back to
> neutral, or 128.
> 
> So say you had a plugged cat.  The reduced airflow
> will cause the INT to
> drop and cut back on fuel.  Since the INT is
> consistently below 128 then
> BLM starts to drop also.  As the BLM drops and cuts
> out fuel, it allows
> INT to rise back around neutral.  So right after it
> plugs you'll see
> normal BLMs but low INTs.  As time goes by (maybe a
> few minutes?) you'll
> see BLM drop and INT rise back to neutral.  Then the
> opposite happens
> when the cat is fixed, and eventually both of them
> rise back to near
> neutral.
> 
> Generally BLM is a table indexed by MAP and RPM,
> like the VE table.  I
> think there are exceptions where there is one BLM
> number for idle and
> another for everything else.  Not sure about your
> specific situation.
> 
> --steve
> 
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> 



		
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