Tuning question for 730 ECM

[Dave Zug]

----- Original Message -----
From: <timsiford at hushmail.com>
To: <gmecm at diy-efi.org>
Sent: Saturday, October 14, 2000 5:38 PM
Subject: Re: Tuning question for 730 ECM


> >78 MPH is it?
>
> As pulled from the HAC...
> L831D: FCB 76 ; UNLOCK PREVENTION THRESH, (76 MPH)
>
> >If you change the parameter, the computer might be defeating your attempt
> >since some of the RPM readings (therefore perhaps others as well?) will
> >change themselves *internally* back to 4800 when the RPM is at 4800
> >or above. I dont know if speed acts this way in certain cases - I only
> >know this from being in the room when someone else was pouring over
> >the code for another reason.
>
> Dave - that's interesting.  I am saying that because I believe that the
> TC still locks up even if you modify the MPH and make it higher.  Could
> you give more detail on what you said about RPM readings changing
internally?
>  I'm not quite following you but I want to :-)

In the code, there are commonly checks that go on just before a table is
acccessed. If the max entry row or column (or one of the 3d variables)
is exceeded by one of the items being used as a lookup parameter, that value
will be forced to the max value for that table.  If a table uses 40 to 160
LV8
as its min and max, a value of 240 for LV8 will be converted to 160 just
before entry.  in instances, this is so that the logic in the lookup
subroutine does never
receive a value beyond what it can find in a table.  I re-read that, I hope
its clear enough. This is NOT to say that the byte(s) for , say, RPM will be
changed, but the value that that particular subroutine sees as RPM will be
changed.

>
> >Watch out with some of those software packages - the position and scaling
> >of a byte can be wrong... CROSS REFERENCE THE CHANGED LOCATION
> > WITH THE HAC's! doing this can save you some headaches.
>
> heh heh ... no problem there :-)  I'm the one who referred TC to put this
> parameter into the definition file.  I pulled it from the anht_hac.pdf on
> ECMGuy's site.
>
> Tim

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