On Tue, 4 Apr 2000, Shane Moseley wrote:
[...]
> > To those DMLers who are interested, let her rip on the presented info. and
> > conclusions.
>
> I've read this exact text before but can't remember the source. Could it be that
> magazine on nothing but Fuel Injection put out by Peterson (I think) several
> months ago? Just a guess. If so - that info was largely GM related - not sure
> about the 128 stored in the block learn mode (sounds GMish to me).
[...]
That does make sense though. Assuming an unsigned 8 bit system, the
values for any variable can only be 0-255. (Or 1-256, if you prefer.)
Assuming the system is indeed unsigned, negative values aren't possible,
thus 128 being right in the middle, becomes zero. Anything less than
128 is essentially negative, and anything above positive. It sounds to
me like its just their way of designating -128 through 128 as an unsigned
integer. A fairly common technique in (simple) embedded systems
programming.
>Anyway, we
> indeed do have what scan tools call a "Long Term Fuel Trim" that I assume gets
> stored somewhere in the computer. I believe that a learned computer will provide
> more power than an unlearned version but the learning is mostly done while easy
> drivin I agree. Since they are relative to rpm and map - perhaps hard driving
> helps learn the higher quadrant quicker and this is how the myth started. I do
> understand that PE mode might disable the learning but believe me - the computer
> doesn't stay in PE for long. For example if you stab the throttle and keep it
> nailed to the floor. Maybe for the first few seconds you are in PE but then
> closed loop takes over and you'll be learning those higher quadrant (high rpm -
> high load) cells rapidly due to the constant TPS.
[...]
I don't really have any knowledge about the exact workings of the
computer programming, but speaking from experience at the dragstrip,
both Bill Tierney and myself have found that (at the dragstrip),
resetting the computer will result in progressively faster runs. For
example, if you reset the computer and run a 15.00, then run again,
it might be a 14.95, then your next run a 14.90, etc. At some point
this trend stops, but we have noted this behavior time and time again.
(If you're into bracket racing, you may want to reset your computer
every time.) Anyway, the only non-WOT throttle operation after the
computer has been reset involves driving through the staging lanes. In
a previous post, it was suggested that WOT would halt the learning
process. Either that isn't true, or the learning that takes place is
simply from idling through the staging lanes. ? Whatever the case,
the computer definitely gets faster on each run after being reset.
>
> Cool conversations for sure - Jon must be lovin it - right Jon?
[...]
Absolutely! Bring it on! =)
-Jon-
.--- jon@dakota-truck.net -- or -- stei0302@cs.fredonia.edu ------------.
| Jon Steiger * AOPA, DoD, EAA, MP Race Team, NMA, SPA, USUA * RP-SEL |
| '92 Ram 150 4x4 V8, '96 Dakota V8, '96 Intruder 1400, '96 FireFly 447 |
`---------------------------- http://www.cs.fredonia.edu/~stei0302/ ---'
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