[Diy_efi] Re: Diy_efi digest, Vol 1 #341 - 12 msgs

[Eric D Byrd]

Thank you Bill W.,

Yeah, recently an acquaintance told me off-list that a CC needs HC fumes
just to operate, and I wondered what it did during closed loop.  I'm
guessing the oscillation can't be avoided with an integral feedback
circuit (I assume that's what kind it is, because that kind can cause
oscillations), but what the heck, you need the rich periods anyway, so
why change the algorithm.

Eric

On Wed, 06 Nov 2002 12:30:50 +1100 Bill Washington
<bill.washington at nec.com.au> writes:
> Eric,
>     The oscillation to rich is not an anomoly in the system, it is a 
> 
> requirement of the CAT. I read recently somewhere that although the 
> CAT 
> can cope with lean operation it requires a rich pulse every 1-2 
> seconds, 
> IE they don't like either continuous lean or continuous rich 
> operation.
>     That being said, mine oscillates continuously at a much faster 
> rate 
> than that (I'm guessing ~5 times a second).
> 
> Regards
> Bill
> 
> 
> 
> 
> 
> >--
> >
> >Message: 4
> >To: diy_efi at diy-efi.org
> >Date: Sat, 2 Nov 2002 11:21:39 -0500
> >Subject: Re: [Diy_efi] New to list, have a question about speed 
> density and turbos
> >From: Eric D Byrd <klox at juno.com>
> >Reply-To: diy_efi at diy-efi.org
> >
> >First, I have studied basics of feedback control, and if the system
> >oscillates, there are ways to achieve tighter control with less 
> tendency
> >to oscillate.  I would speculate that the closed loop methods 
> currently
> >in use themselves make use of the most primitive control 
> algorithms,
> >because of commercial/mass production reasons.  Second, I've seen 
> how a/f
> >meters, the ones with led lights, operate, and they seem to 
> oscillate
> >with a period much faster than 2 seconds, which leads me to suspect 
> that
> >a better wideband sensor might be used to better effect, with a 
> more
> >effective control algorithm with much less oscillation about the 
> target
> >point.  Third, if the answer were obvious to me, I would not have 
> asked
> >the question.  At this point I don't even remember what the 
> question was;
> > in fact what I remember is that I suggested a good final goal 
> would be
> >to try to create a closed loop system of fuel control under boost 
> with a
> >wbO2 sensor.  Not at all a ridiculous idea, or one that would be
> >instantly ruled out by a basic understanding of EFI, as you 
> suggested. 
> >And at the risk of repeating myself, if manufacturers always did 
> things
> >the best way, there would be no need for forums of this kind.  And 
> since
> >the logic of this assertion apparently wasn't clear the first time 
> I said
> >it, I will spell it out.  The fact that there are hundreds or 
> thousands
> >of people trying to put together their own EFI projects on mailing 
> lists
> >like this one, is pretty telling proof that manufacturers do not 
> always
> >do things the best way.  Defense rests.
> >
> >Otherwise, I will not get into an argument about people asking 
> questions
> >that are already covered in basic sources.  The reason people ask 
> such
> >questions, is that they are hoping to find out without spending 
> hours
> >poring over the basic texts.  It may well be that they will decide 
> they
> >want the kind of deep, complete information that such study would 
> yield,
> >but in the meantime, it is no crime for them to ask such questions, 
> and
> >if a member of the list were irritated by the basic questions, they 
> have
> >the reasonable option to ignore the questions, delete the message, 
> get on
> >with their own more profound researches.  There is not one 
> knowledgeable
> >person in existence, about any subject, who was not once a rookie
> >himself, and I would speculate that almost every one of those 
> people at
> >one time or another asked a very basic question that is covered in 
> basic
> >manuals.  Therefore, it would be hypocritical for any one of those 
> people
> >to get up in arms because a rookie asks a rookie question.  To the 
> more
> >experienced person, I might well say, answer the question, or 
> ignore it,
> >but curb your impatience, because that is, in all likelihood,
> >hypocritical.
> >
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> 
> 
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