[Gmecm] BLM cell confusion
WopOnTour
wopontour
Sun Nov 13 05:05:18 UTC 2005
Gary
This post has me a bit stumped
What about the other 13 cells?
Don't ALL of the OBDI calibrations use at least a full 16 cell BLM map?
(4cells by 4cells) Cells 0 thru 16 ??
I know some others like the Quad4 ECMs use 16 PLUS and additional 4 cells
(17-20) that depend on "in-gear" state and AC clutch status.
I've never heard of a GM calibration with only 3 cells...
WopOnTour
----- Original Message -----
From: "Gary Evans" <gary at garyandliz.com>
To: <gmecm at diy-efi.org>
Sent: Thursday, November 10, 2005 11:34 PM
Subject: Re: [Gmecm] BLM cell confusion
> 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
>>>> 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
>>>>>
>>>>> _______________________________________________
>>>>> Gmecm mailing list
>>>>> Gmecm at diy-efi.org
>>>>> http://lists.diy-efi.org/mailman/listinfo/gmecm
>>>>>
>>>>
>>>>
>>>>
>>>>
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>>
>>
>>
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