O2 sensor oscillations

[mrvette]

Bruce, from reading the below, it sounds as if you are running one on a bench,
not an operational engine, is this correct?  if it is, than your comments seems
to make sense, as that is what would happen on a bench...as a dynamic running
system on an engine, there would have to be something wrong,   ....GENE

Bruce Plecan wrote:
> 
> -----Original Message-----
> From: Greg Hermann <bearbvd at sni.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Thursday, October 22, 1998 9:46 AM
> Subject: Re: O2 sensor oscillations
> 
> >>OK, Here's a question:
> >> I read that, while in closed loop - the voltage on the O2 sensor is
> >>supposed to cross 0.45 at some particular rate.
> >>
> >> Are these crossings producted by "puffs" of exhaust going across, or is
> >>the ECU intentionally running lean-rich-lean-rich-lean in order to keep
> >>the avg mix (over time) "centered" on the ideal?
> >>Thanks!
> >>-Bill
> >>I dunno, but some time with a scope hooked up to look at the frequency of
> >>the crossovers vs ignition spark frequency might well begin to give an
> >>answer--anybody???
> >Regards, Greg
> >
> Running car-no.  Final info.-no.  As things look, right now, on the
> bench the ecm looks for a +v at a particular time, in ref to a ignition
> event, as seen by the O2.  TBI, much less picky then TPI.
>   This O2 feedback to ecm is a pain.  +v is a function of inj PW,
> and a time delay, from when Int changed.  Maybe the duration of v+
> will work, but it's a guess for now.
>   With the 747 I used a 555 on after delay and read off an inj fire
> signal.  Would kinda go closed loop properly but after time would
> go open, and wierd IAC BL INT numbers.
> Bruce

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