WPSLPGExhaust Gas Oxygen (EGO) sensor Information

[Bruce Plecan]

----- Original Message -----
From: "Bernd Felsche" <bernie at innovative.iinet.net.au>
To: <diy_efi at diy-efi.org>
Sent: Thursday, August 03, 2000 11:51 AM
Subject: Re: WPSLPGExhaust Gas Oxygen (EGO) sensor Information


> Steve Schwartz tapped away at the keyboard with:
>
> > I am going to jump in with my first post to this list. No Fear!
>
> > This oscillation, duty-cycle, frequency stuff is IRRELEVANT.  This
> > discussion lacks a clear question!  What are we trying to
> > accomplish?  I saw mention of WOT performance in open-loop mode.
> > Is this what we want the EGO sensor to tell us?  If so, indeed, we
> > need only 2 LEDs - RICH and LEAN.  Note that this is in OPEN-LOOP,
> > i.e. no feedback path to drive the mixture toward stoichiometric.
>
> That's a good starting point IMHO. At WOT you might also just want
> to make sure that you're actually fuelling on the rich side. So that
> sort of closed-loop control (sanity-checking basically) could be
> useful, especially if the ECU doesn't otherwise self-calibrate the
> AFR on a modified engine.
>
> It's not so much a matter of how rich, just the knowledge that
> you're putting enough fuel into the engine is probably sufficient at
> WOT for a road car. (Different ball-game altogether for aircraft,
> boats, and the like I expect.)
>
> > 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
Grumpy

> Specs have sensor response times as fast as 50ms (OK, that's not
> really fast); others IIRC have typical response of up to 200ms.
> Siemens were doing some research on this about 10 years ago. They
> claimed that they could respond to the gas change due to overlap at
> medium engine speeds (up to about 3000rpm from memory) if one sensor
> was fitted per cylinder.  I haven't stumbled across further
> information on the devices.
>
> [snip]
>
> > So, let me ask the following:
> >
> > What are we trying to do?
>
>
> --
> Bernd Felsche - Innovative Reckoning
> Perth, Western Australia
> --------------------------------------------------------------------------
--
> To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org