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RE: Adaption in OBD-II and questions
- Subject: RE: Adaption in OBD-II and questions
- From: Land Shark <lndshrk@xxxxxxxxxxxx>
- Date: Thu, 19 Nov 1998 15:29:15 -0700 (MST)
> From: "Neil Deshpande" <[email protected]>
> I wonder if I am correct. Jim?
Actually, the car adapts so that any operation in it's adaptive
ranges reverts to lambda one.. so if you enrich the wrong areas
of the part throttle maps you waste your time and actually
are ENLEANING the wot map!
> 1. Does the chip rewrite itself only after the car is switched off or is
> it changing on the move. The latter would mean it is impossible to get
> dyno numbers even if you clear adaption. You would have to cancel the =
> adaption process altogether. Is this even fair to the chip?
What we do is actually clear adaption then DISCONNECT all four sensors
running the car until the CE light illuminates (about 0.001 sec on
those darn M3's ;)
Then test...
Then tune..
Then repeat
> 2. Aren't there adaptive transmission chips too?
I couldn't answer that one.. but I have recently joined
with someone who is a guru in the Transmission field, and
he's working on some special trans chips for me.. I'll ask him
> 3. Does the chip improve noticably after only one run and how many HP?
It might get worse if were incorrectly calibrated.. forget what
you have read.. the DME doesn't adapt to "driving style" or any other
such nonsense.. it adapts to EMISSIONS criteria.. and if you do
everything JUST right.. once the chip is adapted to the actual
engine particulars of the car.. it only changes for weather
> Will the stock OBD II chip ultimately get near as good as a Jim C. chip
Not even close.. the chip isn't adapting to the way you drive ...
It works like this (again.. these are EXAMPLE, not REAL numbers)
Let's say the adaptive range is 1000-3000 rpms.. throttle less than
50%...
You're in traffic.. 1/3 pedal.. 55mph, 5th gear.. SMACK in the
range.. the O2 sensor is seeing if it has to go RICH or LEAN
more than the opposite.. and if it does for some amount of time
then the adaptive trim changes in the opposite direction by the
needed percent to "center the window"..
Once that number is created, though.. even if you are running
full throttle 4th gear at 6000 rpms.. the number is still USED
In general.. as the car runs.. it gets slightly leaner because
all maps are tuned *slightly* rich for safety..
Adaption cannot change the spark advance to increase it.. only
to decrease it from that which is programmed..
Adaption doesn't increase performance...
> 4. What kind of percentages does the change involve? I would guess
> there is a limit imposed by BMW on the amount each parameter can
> change.
ADAPTION can change the mixture (generally) up to +/- 25%
> These would be the limits that Jim C. woud reoptimize in his chips.
> Right?
No.. by tuning outside of the adaption areas I *COULD* double the
fuel if I wanted to.. although it would be a sign of insanity ;)
The problem isn't a lack of adjustment.. it's a lack of stability
when testing the vehicle!
Jim
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