[Gmecm] Buick 3300 LG7 MAF Program...

[David Allen]

You definately do know these ECM's inside and out. Very impressive!  
Sincerely,
David

  ----- Original Message ----- 
  From: Robert Saar 
  To: gmecm at diy-efi.org 
  Sent: Saturday, November 10, 2012 7:40 PM
  Subject: Re: [Gmecm] Buick 3300 LG7 MAF Program...


        and here's the quick run-through of the MAF HZ calculation.

        3FC6 (only used in this subroutine) - no actual purpose other than to grab value and compare it to itself to see if 3FF8 should be grabbed again
        3FF8 (only used in this subroutine) - stored to AA
        double byte 11A - old AA value. gets loaded, then inverted via NEGA/NEGB, A rounded, then AA added to it, then stored to AE
        double byte AA - current 3FF8 value. copied to 11A(delta?).
        double byte AE - is AA + inverted 11A
        double byte 11C - old AC value. loaded, inverted, A rounded, AC added, compared, then divide with AE
        double byte AC - current 3FC6 value. copied to 11C(delta?).


        11C is inverted, then AC is added to it, compared against a few values, then the divide with AE, creates 16-bit Hz X 1



        now, the two big hardware locations are 3FC6 and 3FF8, both of which i've noticed in A1 already, so that's good news. in the 2E hack, 3FC6 is noted as "PA2 counter", so it is a pulse accumulator. it now makes sense how all of these values are intertwined. 3FF8 is also used in 2E in basically the same manner as well. the 2E PCM(used in 94-95 3.4DOHC W-bodies is basically an underhood version of the 94-95 3100 A-Body PCM) is also a P4 unit, so all of this is checking out quite well.

        also, the AE XDF that is floating around on the internet? it's not quite accurate.... not sure where it came from, but from the couple of things i've specifically looked at, there are some changes that need made to be correct. the MAF tables were one of them. $AE is limited to 256 grams/sec (2E is limited to 512 grams/sec due to having a MAF table scalar and offset).

        --- On Sat, 11/10/12, David Allen <davida1 at hiwaay.net> wrote:


          From: David Allen <davida1 at hiwaay.net>
          Subject: [Gmecm] Buick 3300 LG7 MAF Program...
          To: "David Allen" <davida1 at hiwaay.net>, robertissar at yahoo.com, "GM-ECM" <gmecm at diy-efi.org>
          Date: Saturday, November 10, 2012, 11:29 AM


          Hi Robert. Attached are 2 .bin files. My chip reader wouldn't auto-detect the chip size, so I read it as a 27C256 and as a 27C512. If these are not usable I can adjust and read it again. Normally it auto detects the chip size, so I hope this doesn't mean the chip was corrupt or damaged.

          This MEMCAL (AXAT 9713) was installed in the 8706 ECM I got from junkyard from a 90's Cutlass Ciera 3300 car.

          Hope this helps you to improve your nAst1 code MAF function! Will be interested to hear what you find.

          Sincerely,
          David 

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