[Gmecm] BLM cell confusion

Tue Nov 15 01:21:44 UTC 2005

Gary
I was pondering your comment regarding the differences in the DIS versions 
of the GM code, and being unable to find a DIS compatible code.
Have you ever looked at the Quad4 code versions for the '749? ($5C??)
Unlike the 2.0L turbo and $58 these engines used the same ECM but were 6+1 
DIS
At the very least maybe there's a way to see what they did differently?
Regards
WopOnTour

----- Original Message ----- 
From: "Gary Evans" <gary at garyandliz.com>
To: <gmecm at diy-efi.org>
Sent: Monday, November 14, 2005 2:32 PM
Subject: Re: [Gmecm] BLM cell confusion
SNIP

 > As for the 6+1 crank trigger, there have been lengthy threads in the
> past on the differences between the DIS and distributor code. Despite  the 
> similarities in wiring and theory of operation, the distributor  and DIS 
> codes expect slightly different things to be happening on the  signal 
> lines. There is a difference in the timing and dwell  calculations that no 
> one ever seemed to figure out (or if they did, I  missed it). Of 
> particular interest is this line:
>
> 801B        AA    170 KREFANGL 59.8 DEG SPARK REFERENCE ANGLE
>
> I read about the trials of another GMECM member trying to get DIS to  run 
> on distributor code, decided it wasn't worth blowing up my  engine, and 
> went with the $a1 code instead.
>
> This google search will lead you to some of the old threads on the 
> subject:
>
> http://www.google.com/search?q=gmecm+dis+distributor+base+reference +angle
>
> -Gary
>
>
> On Nov 13, 2005, at 1:16 PM, WopOnTour wrote:
>
>> Gary
>> Nah, you're kidding right? I realize the $88 and $1A calibration  details 
>> concern itself with cells 0 and 1 a lot for as these are  idle cells, but 
>> I've had a TECH1 scan tool on hundreds of those V6s  and the BLM cell PID 
>> varies between cell 3 and cell 15 at road  loads. What scan tool do you 
>> use??
>>
>> Also, what difference does the style crank triggering make to the  ECM? 
>> That's all resolved by the DIS module itself AFAIK (well  except on the 
>> newer OBDII models where the CKP is hardwired  directly to the ECM) On 
>> the 122730/727 the ECMs onlly connection to  the ignition system is the 
>> EST and BYPASS and the ECM doesnt care  what triggering methods 
>> (distributor or DIS) are being employed, as  the CKP is connected to the 
>> DIS module not the ECM.
>> Please explain
>> WopOnTour
>>
>> ----- Original Message ----- From: "Gary Evans" <gary at garyandliz.com>
>> To: <gmecm at diy-efi.org>
>> Sent: Sunday, November 13, 2005 1:13 AM
>> Subject: Re: [Gmecm] BLM cell confusion
>>
>>
>>> No really, they exist. The $a1 and $88 masks for the 2.8 / 3.1 V6 
>>> engines use only 3 cells. There are probably others, used  primarily  on 
>>> "low budget" applications. The customary masks to  work with ($8d  for 
>>> example) are performance oriented, so the 16  cell calibrations  are 
>>> better known in the GMECM community but 16  cells are by no means 
>>> standard across all applications.
>>>
>>> If I was going to start from scratch on my project again, I would 
>>> definitely try to use one of the other masks that offer the usual  16 
>>> BLM cells. IMHO, the $a1 and $88 code bases are sloppily  written and 
>>> not very easy to tune. I am no assembly expert, but  from the work I 
>>> have done on the $a1 hac, the code appears to be  a mess. Example: the 
>>> injector constant is part of one of the EGR  tables. yeah.....
>>>
>>> However, I need the 6+1 crank trigger DIS, and as far is I know  $88 
>>> $8F and $A1 are the only masks that support it out of the box  on the 
>>> V6. If there is another mask that supports 6+1 crank  trigger, DIS, 
>>> *and* 16 BLM cells, I would love to hear about it  because I am  getting 
>>> the itch to do more tuning on my car, and I  might be inclined  to try 
>>> something new if it offered better  tunability and cleaner (or  maybe 
>>> just better documented) code.
>>>
>>> -Gary
>>>
>>>
>>> On Nov 12, 2005, at 9:05 PM, WopOnTour wrote:
>>>
>>>> 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
>>>
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>>> Gmecm at diy-efi.org
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