O2 sensor oscillations

[Bruce Plecan]

-----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