O2 / Lambda Sensor Data

[Bruce Plecan]

2 cars is hardly enough to start making universal generalizations.
If you would care to read the archives you'll find out alot more about them.
If you repeated your experiments by reading the plugs you'd have saved more,
and been more accurate
Bruce


> With respect to what other have written, the science does back up what
> everyone has said, but I believe that lambda sensors can be successfully
> used as an very cheap aid to engine tuning. I talk from hands on
experience.
> A friend and myself have been working with lambda sensors as a means of
> obtaining an indication of mixture with some very interesting results.
Some
> background:
>
> Two cars, similar states of tune. Same engine, management, exhaust, inlet,
> grade of petrol etc. etc.
>
> An addition lambda sensor was installed into the exhaust down-pipe
adjacent
> to the factory one. This was achieved by drilling and welding a boss in
> place. Two different sensors were used, a Bosch one and a webcon pattern
> one. Both heated (2 wire heater, 1 wire signal, signal ground via exhaust
> itself). Two lambda sensor "meters" were made, from the kits designed by
the
> "Silicon Chip" magazine in Australia. These use a PIC which has the volts
> 'v' mixture curve table and outputs a air/fuel figure between about 11.5
and
> 16.5.
>
> The cars run Motronic M1.5 which only really goes into "open mode" at WOT
> (wide open throttle). We made a series of EPROM'S which contained
different
> WOT fuel maps, each one adding a few ms onto the injectors duration at
WOT.
>
> It was possible to place one chip into one car, warm up the sensor for a
> good few minutes, you can see when it is nice and warm as the open loop
> cycles between 14.6,14.7,14.8. At WOT the meter "locks" onto a fuel ratio
> which stays pretty constant through the rev range.
> The same chip in the other car gave the same results! Add a chip with more
> fuel at WOT and up goes the meter reading! Replace it with a chip with
less
> fuel at WOT and down goes the meter reading. Repeatable results, even on
> different days. I think that the temperature of the sensor is quite well
> regulated and constant enough to give some meaningful results EVEN off
> stoichiometric. Not state of the art I agree, but for a total cost of less
> than 60quid for sensor and meter it can't be beat IMHO.
>
>
> P.S. Some quick pictures of the installation can be seen at:
> http://www.btinternet.com/~wreeve/afmeter.htm excuse my lucky mascot!
> P.P.S. The reason we went to all the trouble was because we removed the
cats
> and replaced all the silencers with straight through versions, did a bit
of
> head porting, and fitted a free flowing air filter....this we thought
might
> have changed the fuel requirements at WOT. Because a) the lambda sensor is
> ignored, and b) the AFM is ignored. This turned out to be a good
assumption
> as at standard settings the WOT mixture was BELOW stoic, its now set up at
> around 12 and lower at WOT!
>
>
>
> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Bruce Plecan
> Sent: 25 April 2001 16:01
> To: diy_efi at diy-efi.org
> Subject: Re: O2 / Lambda Sensor Data
>
>
>
> All the one wire ones can reliably do is tell you when your rich (over
.5v),
> or lean (less then).    Anything else is like reading tea leaves.
> When your done tuning, you might record what O2 voltage is was, and a
> general reference but again, it's very general
> Bruce
>
>
>
> > I'm after some data on a 1-wire O2 sensor.  I'm planning to construct
the
> EGO meter
> > as per diy-efi web site, but I still have some questions
> > I'm planning to use a universal 1-wire sensor. But I can not find any
> technical
> > data on them.
> > 1.  Does the sensor require a bias or excitation voltage?
> > 2.  If the output voltage is self generating (albeit at high impedance)
> what
> > voltage corresponds to what oxygen level?
> > 3.  what is the correlation to oxygen level and mixture ratio?
> > I have already built the circuit but have yet to buy a sensor, any
> recommendations
> > would also be appreciated.
> > Thanks.
>
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