WPSLPGExhaust Gas Oxygen (EGO) sensor Information

[rr]

Greg,

Really, then what is the proportional term that is calculated from the
O2 sensor value over time vs. the desired value used for?

BobR.

And the INT is not the Integral? (contradicting myself from an earlier paper)

Greg Hermann wrote:

> There is absolutely no way that the sensor input in the factory ecu's could
> be characterized as either P, PI, or PID, or any of the various possible
> permutations thereof!
>
>  It is NOT banb-bang in the sense of fuel on--fuel off, it is bang-bang in
> the sense of bang--begin reducing injector duty cycle relative to the
> mapped value for the particular engine operating point if rich; bang, begin
> increasing the injector duty cycle relative to the mapped value for the
> particular engine operating point if lean. This is done with a multiplier
> that is used, and increased or decreased progressively, on a bang-bangt
> basis, across all mapped engine operating points during transient operating
> conditions.
>
> Sorry, but I thought that the part about sdjusting the duty cycle was self
> evident!
>
> Suggest you not try to throw around textbook vocabulary in an attempt to
> make a point here, unless you have a _VERY _ thorough understanding of, as
> well as working experience with, what you are talking about!
>
> Greg
>
> >Sorry, Greg, but I must disagree.
> >
> >The 'bang-bang' control you refer to would be fuel_on - fuel_off.  The fact
> >that the EGO can only accurately report RICH or LEAN, has no bearing on the
> >control algorithm.  The ECU maintains an injector DUTY CYCLE, which is
> >constantly adjusted, in small increments, up and down, to keep the EGO
> >crossing the stoich point.  PROPORTIONAL control, possibly with an INTEGRAL
> >term, under some conditions.  That is the ONLY way it can know that the
> >AVERAGE mixture is NEAR stoich.  The control algorithm has nested loops, if
> >you will.  I suppose you COULD look at TPS response as a DERIVATIVE term,
> >but we digress...
> >
> >New and interesting info:
> >
> >> three way CAT PERFORMS BEST if the gas coming through it
> >> alternates between
> >> a bit rich and a bit lean.
> >
> >I didn't know this!  But it has a ring of truth.

<snip>

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