Individual Cylinder AF Adjust, was: NTK wb-sensor price

[Bruce]

While two cycles may not be exactly the same, there maybe *trends* involved.
Seems odd GM would go to individual cylinder trim, if there was nothing to
be found.   As I recall in some cals, the correction is a constant (not in
any learn cycle strategy).
Bruce




----- Original Message -----
From: "Axel Rietschin" <Axel_Rietschin at CompuServe.com>
> ...probably, but I just ask myself, why would you want to do so?
Apparently
> there is a lot of cylinder to cylinder variation and no two cycles are the
> same (at least Heywood says so, see Sec. 9.4.2). By trying to be super
> selective you may end up trying to correct for something that already
> happened and will most certainly not happen again in the immediate future,
> one single cylinder apparently being able to randomly jump over a few
"AFRs"
> from one cycle to the very next all by itself (for various reasons well
> beyond ECU control, for example the mixture composition in the vicinity of
> the spark). I suggest that you may well end up making things worse by
trying
> to adjust the fuelling this way (I actually made some tests, if you are
too
> "nervous" in the control loop (lots of P-gain, trying to react as fast as
> possible) it never stabilizes. I got better results (as far as "mixture
> stability" goes) with gentle correction and some filtering to actually
> smooth thing out)
> just my 0.02 ?
> Axel


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