WPSLPGExhaust Gas Oxygen (EGO) sensor Information

[Bernd Felsche]

Bruce Plecan tapped away at the keyboard with:

> ----- Original Message -----
> From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
> > > If, as in the example at
> > > http://www.cnnw.net/~fourty/uses.html, we are in CLOSED-LOOP,
> > > i.e. an operational EFI system, the oscillation is caused by
> > > the control algorithm varying the mixture to stay as close as
> > > possible to stoich.  The injector pulsewidth is constantly
> > > being adjusted to make the O2 sensor cross the stoich point:
> > > leaner if too rich, and richer if too lean.

> > Is it not possible that at low speeds, that any scavenging effects
> > (valve overlap) *could* also cause the sensor to "blip" to lean as
> > it gets a whiff of fresh air?  Or is it too slow?

> Overlap might be what at .050 lift (pick any sensible amount for any sign.,
> flow to start) 3-8d?.  Not even enough to weight in with

Don't know the lift at 0.050 (presume inches). The spec's I have
specify duration at between 0.2 and 0.5mm. e.g. Kent Cams are
specified at 0.4mm lift (around 0.015") on a fast-road 270 degree
cam - so how much overlap does that come to? I don't know; I'd have
to measure it to be sure.

Assuming that I have one quarter of the numerical total "excess"
above 180 degrees (in this case 90 degrees) as the timing for IO/EC
relative to TDC, that puts the overlap at 45 degrees. Looks like too
much - but then again, that's at 0.4mm lift.  Even at one-third of
that to *approximate* 0.05" lift, you still have 15 degrees of
overlap.

A tuned inlet can have a pressure pulse arriving as inlet opens, and
if that is greater than the residual exhaust pressure at that time
(perhaps aided by a tuned exhaust) then you will get significant 
scavenging resulting in a significant amount of O2 in the exhaust.
The amount will depend on a large number of factors.

But the question remains; will the O2 sensor pick it up? Will it
switch to lean?

Maybe I should make a harness adapter and check it using a 'scope.

-- 
Bernd Felsche - Innovative Reckoning
Perth, Western Australia
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