[Diy_efi] changing wbo2 reading via timing

[Adam Wade]

--- Erik Jacobs <emj14 at columbia.edu> wrote:

> Uh... doesn't it MAKE SENSE that the wbo2 reading
> would change with a change in timing?

Yes, for exactly the reason I believe that four-gas
beats the pants off of O2 sensing; CO is a far better
gauge of optimal mixture than residual O2.

> I mean, if you change your spark timing, can't it
> end up effecting the actual extent of the combustion
> that occurs?

Absolutely.  Whether that has anything to do with
whether your mixture is correct or not is another
story...

> Like in an extreme case, if the spark was way late
> (super retarded), you'd completely miss TDC and may
> not get any ignition at all, which would result in
an
> extremely rich mixture reading as the whole charge
> passes out thru the exhaust valve...

Nope.  It would result in an extremely LEAN mixture
reading, using an O2 sensor.  Because there would be a
great excess of both O2 and HC in a case like that. 
And both HC and O2 readings, by themselves, would not
tell you much of anything about whether the mixture
was correct (in fact, NOTHING could with a significant
misfire condition, but at least looking a 4-gas, you
could clearly tell it was misfiring just by looking at
the gas readings).

My point was that best mixture doesn't change when you
vary timing; while you might get some slight
improvement in power with non-optimal timing by making
small changes in A/F, you can't get down to brass
tacks with residual O2 alone, especially when timing
is in question.

=====
| Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
|   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |

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