At 10:53 PM 4/3/00 -0500, you wrote:
>A lot of it has to do with how you drive it to, if the computer learns
>your driving style to be fast, it will put out more power. If you "putt putt"
>around town, then go to the track, the computer is less likely to put the
power
>to the ground.
I'm submitting this information to generate a discussion. Dakota/Ram
computers
may not work in the same way down to the last detail but I think our computers
follow this overall programming structure. The next 5 paragraphs are tech
type information and is followed by a summary in layman's terms (I hope).
The computer contains two things responsible for learning - a short term
memory
and a long term memory. The only thing that is stored and memorized is
what is
in long term memory. Some computers use 16 'long term' cells numbered 0-15
that
are separated into a grid by RPM and MAP. As you rev the engine you "travel"
through this grid and hit various cells. 0 is the idle cell and 15 is the WOT
cell. These cells are not a part of the serial data stream so scan tools
are not
able to indicate which cell you’re in. They will, however, give the value
of the
current cell.
The O2 sensor will detect a rich/lean condition, and cause the short term
memory
to change. The long term memory is simply a long term average of the short
term memory.
128 is a normal number, signaling no change. A number greater than 128
reflects a lean
condition, and a number less than 128 reflects a rich condition.
Only the long term memory is saved and memorized. The short term resets on
start-up
and is constantly changing. By clearing the computer memory the long term
cells are
reset to 128. The long term memory cells are the ONLY thing the computer
memorizes
and are totally related to how the O2 sensor detects the fueling to be,
thus the the
computer does not learn or detect things such as driving habits. The O2
sensor considers
a stochiometric air-fuel ratio (AF) of 14.7:1 to be optimum.
Should you be driving fast and accelerate hard to learn in the computer?
No. By always accelerating hard you’ll never learn in the computer. This
is because
you’ll be in Power Enrichment (PE) mode. Once you’re in PE, Learn-mode is
turned off.
About 10 minutes of normal, easy driving in stop & go traffic is sufficient
to learn
in the majority of the long term cells.
Power enrichment mode is where additional fueling is given to run a richer
AF mixture
than stochiometric. The system remains in a "Closed Loop" mode but ignores
the O2 sensor,
essentially running "open loop" under a "Closed Loop" mode for lack of a
better term.
On a scan tool, the "Closed Loop Mode" indicator will still indicate closed
loop, however,
the short term cells will be reset to 128 and Learn-mode will be off. The
long term value
displayed will be the value used in the fueling calculations, and will
usually, but not always,
reflect long term memory cell 15 (depending on RPM and MAP). It is the last
value learned in
before entering Power enrichment mode.
SUMMARY.
The only thing that the computer stores are long term averages of the value
that the O2
sensor has sent to the PCM as it attempts to maintain a stoich mixture
under idle, WOT, etc.
When the computer is cleared, these averages are reset to 128, representing
no change.
The computer does not learn hard acceleration habits because the computer
enters the Power
enrichment mode which turns off the Learn mode during hard acceleration.
To those DMLers who are interested, let her rip on the presented info. and
conclusions.
Bob. Southern Ontario, Canada.
'97 Dakota CC Sport, FR, 5.2L, 3.55 SG, auto.
This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 11:50:36 EDT