[Diy_efi] Making a fake O2

[Mike]

mmm, 

I seem to recall someone on this list talking about storage cat system
and EFI some 2 years back,

ie. The EFI ECU drifts rich and lean to force the catalytic convertor
to do its job properly for a storage type cat, I'm not familiar with the
precise algorithm or even the cat cycle but I recall that even for
optimum air fuel ratio the ECU will force lean/rich/lean cycle over
a longish period of time to most effectively use the cat...

Rgds

mike




At 09:19 AM 29/05/05, you wrote:
>Hello again,
>     I am surprised at the number of responses I got.  Thanks everyone for
>your interest.
>     What I am trying to do is get a look at the base fuel map without
>getting inside the computer.  I've played a lot with GM ecms, and yes
>it is very easy to force the issue in software.  Just set the BLM,
>and INT limits to 128.  It might then see the o2, but it can do
>nothing to compensation for it.  I had a feeling I'd get all kinds of
>responses.  I know I can fake the computer with a simple oscillating
>signal. The real question is if a send a perfect signal, will the
>computer drift anyway.  I'm worried that the signal might be good,
>but the computer will drift a little rich, or a little lean.
>     I'm playing with Honda/Acura OBD I computers at the moment.  The data
>stream doesn't show any form of a trim adjustment being made.  There
>is a fuel map, but not a trim map like what I've seen on the GMs. 
>But the car is very responsive to O2.  A friend of mine has just
>modified his motor.  He said, "Just a minor change".  Yeah right. 
>Forged pistons, higher compression, new cams, etc,..  Well, he's got
>it running.  But it's pinging a lot.  Ha!  He doesn't really
>understand what he has done.  All he is thinking about is power. 
>More power!  Have to have more power! I'm on vacation in Thailand,
>and I told him don't go running it until I get back.  So what does he
>do.  He goes and runs it anyway.  We are now on motor #2, and I'm
>still on vacation.  Now he says its running lean, and so he puts in a
>new set of bigger injectors.  He's just throwing stuff at it.
>     I'm trying to formulate a way to get this thing really right.  I
>don't want to do across the board adjustments.  I've spent enough
>time with the GM computers to see it is never just richen it up.  You
>usually have to pull back some fuel at idle too.  Those bigger
>injectors are great at top end, but not when you are idling.
>    I want to be able to run this thing on the dyno, and get it really
>close to a right adjustment.  And then we can make little adjustments
>on the track.  The problem I was having before was the O2 would start
>adjusting faster than I could be sure I had a good reading at any
>given rpm/map reading.  So I'm thinking got to take the o2 out of the
>equation.  And so here I am...any further thougthts anybody?
>
>Thanks,
>
>Marcello
>
>
>
>
>
>
>
>
>
>
>> Hello everyone,
>>      I have been trying to figure out how to make a computer run on its
>> base fuel map, and not use the O2 sensor.  I was wondering if it
>> might be possible to send a signal that looks like perfect mixture
>> all the time?  A signal that looks like no adjustment need to be
>> made.  You could put this in place of the O2, so you could see the
>> fuel map output without correction.  Is this possible?  I'm figuring
>> do a reset of the computer and install this device.  Then take all
>> your readings.  What does everyone think?  Am I a crazy?
>>
>> Thanks,
>>
>> Marcello
>> _______________________________________________
>> Diy_efi mailing list
>> Diy_efi at diy-efi.org
>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://lists.diy-efi.org/mailman/listinfo/diy_efi

Regards from


Mike Massen
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
http://niche.iinet.net.au