[Gmecm] BLM cell confusion

[Steve Ravet]

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
> 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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> > Gmecm at diy-efi.org
> > http://lists.diy-efi.org/mailman/listinfo/gmecm
> > 
> 
> 
> 
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