[Diy_efi] O2 says rich, car runs lean..

[Michael Richards]

On Mon, 12 Jun 2006 23:26:25 -0400, Daniel Nicoson wrote...

We're producing wideband controllers so I think I can answer this one.
The cycling you are observing is a result of the closed loop feedback.
The sensor reads rich so the ECU removes some fuel then it switches to
lean and the ECU adds some fuel. This is the cycling.

For the narrowband emulation most units just output a signal consistant
with the switching of a narrowband sensor. Some allow this output to be
skewed to force a factory ECU to cruise leaner or richer. This can be
important for fuel economy  or to smooth our a lumpy cam.

-Michael

> Question on the WB's that give NB output.  Is it accurate NB output,
> meaning is it cycling in closed loop showing hi-lo as a real NB would?
>  Or, does it just give a simulated output voltage signal that stay's
> within an acceptable range to not trigger problems?
> 
> With accurate NB output the stock ECM can still do its legitimate
> tuning in closed loop.  If simulated, you may not have the ECM working
> for you in the closed loop operation.
> 
> Curious.  I use a third bung with my DIY-WB sensor and leave the stock
> O2's in place to do their thing for closed loop operation.  Works for
> me.  Just curious how those "store-bought" units work.

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