C/L WB/WOT OEM ECUs...

[Garfield Willis]

On Fri, 31 Mar 2000 11:03:22 -0800, garwillis at msn.com (Garfield Willis)
wrote:

>Q: any way
>to move those useful and inexpensive OEM controllers into the realm of
>WOT closed-loop ECU, once affordable AFR sensing becomes available?

It's entirely TOO quiet around here! :)

After fielding this topic a couple days ago, I've received a bit of
private communication from a few guys that suggested the above was quite
doable. Hmmm. Seems like adopting some short-cut nomenclature is in
order, for those interested in talking about this further. I liked
referring to the subject as one chap styled it, "closed loop OEM
controllers" and another guy's abbrev. of that as "C/L WOT control", so
I've joined them together in the subject line like Cioppino :), which
should make it easier for us to type/discuss. So if we wanna emphasize
closed-loop, we can just type C/L and everyone will know what we're
referring to, or C/L WB WOT OEM ECUs for the whole enchilada,
closed-loop wideband wide-open-throttle OEM ECUs. Take your pick from
the menu.

OK, so yous guys that consider this a slam-dunk, let's get this toad on
the road in public, and light off this thread, eh? Seems we have to
start, as a point of departure, with the basic bug-bear that normally an
OEM ECU keeps to closed-loop feedback ops with the normal switch-type O2
sensor, ONLY until some major throttle pos or MAP/MAF input spells
"significant load/accel", and then the table-driven enrichments and
fueling take over, and the ECU stops listening to the O2 sensor; we're
then in open-loop. Question is, if we want to use a wideband AFR sensor
to control a simulated switch-type O2 sensor input to the ECU at any
commanded AFR "crossing", then HOW do we go about using cal changes in
the OEM ECU, and any other needed tricks, to *contrain* the ECU to stay
in closed-loop and follow the simulated O2 sensor input, to give us
closed-loop control of AFR at any fueling regime we choose.

I can see how one might use an EGOR-module (or NTK box, or whatever) to
set a "commanded AFR", and also how to simulate this AFR as the
"stoich-crossing" to the ECU that's expecting to see a switch-type O2
sensor input, that's the easy part; what I don't fathom completely at
this point is how to KEEP the normal OEM controller, even at significant
TPS/MAP/MAF inputs, from leaving C/L, ignoring our O2 input, and running
outta it's open-loop fueling tables, as it normally would. I'm thinking
that anyone who shows how this trick can be done is going to make a
major contribution to opening up WB WOT to wide application and
experimentation, not to mention bringing the cost way down from the
FelPro's and Motec's.

Anyone wanna light the fuse, and get what's likely to prove a
barn-burner of a thread going? I cain't help; I'm pretty clueless when
it comes to the OEM ECU end of things.

Gar


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