[Diy_efi] changing wbo2 reading via timing

[Shannen Durphey]

LOL!

The "instantaneous residual oxygen reading" is the output of the sensor,
which shows up as a voltage trace on my scope.  Since the scope plots in
time, I see a flat trace at a fixed voltage level when the engine is not
running.  Easy.

Rich running and lean running can look similar, but as a tuner in the same
room as the dyno, I can smell the difference between excess fuel and lack
of same to the point of misfire.  An engine running so rich that all
cylinders are misfiring is almost stalled, and as a tuner if I can't notice
this through other clues than I'm passed out or dead.

And I'm not separating the exhaust gasses out of individual cylinder.  I'm
viewing voltage generated as a feedback by the sensor driver's current pump
circuitry attempting to maintain fixed current flow across the sensor
element in the presence of rapidly changing differential oxygen
concentration.  There's more oxygen passing the sensor during the exhaust
pulse time than durinng the non pulse time.  Reducing scope sample time
sufficiently below the pulse duration will individual pulses.  Watching the
pulses as fueling swings across stoich during closed loop operation in a
feedback efi system, one can plainly see the voltage trend that's tracked
and displayed by tools such as the dynojet wide band display.

Diagnostic procedures for finding a misfire are easy, just like diagnostic
procedures for determining a sufficiently rich engine ( and thereby a
sufficiently lean one ) are easy.  In both cases you need to bring in
"outside" information.  

Shannen

Adam Wade wrote:
> 
> --- Shannen Durphey <shannen at grolen.com> wrote:
> 
> > To be honest, a WB _can_ do the same thing.
> 
> I defy you to look at an instantaneous residual oxygen
> reading that is lean past the end of the scale and
> tell me whether the vehicle is A) not running, B)
> incredibly lean, C) rich misfiring.
> 
> I can look at an instantaneous four-gas plot and tell
> them apart with great ease.
> 
> > I've viewed WB signals with a scope and actually
> been
> > able to see individual cylinder events.
> 
> Since there's no way to separate out the exhaust gases
> of an individual cylinder unless you pipe into a
> manifold runner, I'm surprised to hear someone claim
> that.
> 
> > Like the 4 gas, there's no way to isolate which
> > cylinder is misfiring from the pattern alone.
> 
> If one cylinder is misfiring, the dignostic procedire
> is quick and easy, just like it's always been (unless
> it's an injector problem and you're running
> sequential-fire).
> 
> I opted not to answer your other post about cooling,
> since the pieces of it that were not already covered
> with the opinions of others regarding cooling issues
> were already responded to by myself in previous posts.
> 
> =====
> | 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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