[Diy_efi] Making a fake O2

David Cooley n5xmt
Thu Jun 2 23:09:40 UTC 2005 

That is called "Limp" mode in a GM computer.
The original poster was talking about faking an O2 signal, so there would be
no forced 5% enrichment, only the BARE raw fuel maps in the factory cal.
Again, learn to read.

Fucking morons
 

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Mike
> Sent: Thursday, June 02, 2005 1:30 AM
> To: diy_efi at diy-efi.org
> Subject: RE: [Diy_efi] Making a fake O2
> 
> At 06:17 AM 2/06/05, you wrote:
> >I never said that ANY open loop maps would destroy an engine...
> >My comment was that a computer DESIGNED FOR CLOSED LOOP WITH AN O2 
> >SENSOR if run in open loop only with the O2 disabled will 
> cause damage.
> >Geez people, learn to READ
> 
> Having looked closely at the Hitachi/Bosch ECU for the NIssan 
> RB30E and RB30ET for some 10 years or so  - I really doubt 
> the efficacy of your wild generalisation. This ECU is 
> designed specifically for use with a classic O2 sensor and 
> has many modes that allow it to operate reliably without 
> input from some sensors, in that respect:-
> 
> If the O2 sensor is faulty or missing the ECU runs open loop 
> *plus* makes the mixture about 5% richer overall. ie It still 
> uses the primary inputs of AFM and engine speed to provide 
> open loop fueling but cannot close the loop, therefore it 
> must be open loop - yes ?
> 
> How can this cause damage when it averages 5% or so enrichment ?
> 
> Provide some earnest rationalisation to support your 
> generalisation please ?
> 
> Mike
> 
> 
> 
> 
> 
> >> -----Original Message-----
> >> From: diy_efi-bounces at diy-efi.org
> >> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Marcello 
> A. Belloli
> >> Sent: Tuesday, May 31, 2005 11:28 PM
> >> To: diy_efi at diy-efi.org
> >> Subject: RE: [Diy_efi] Making a fake O2
> >> 
> >> Dan,
> >>     Yes, that is exactly where I am.  The stock computers 
> mapping is 
> >> in no way set up for the engine that is now connected to it.  
> >> Everything you said is right on.  We have a mismatch.  The 
> stock ecm 
> >> and its mapping isn't going to work.
> >>      I have kept reading hoping the bickering would stop.  I agree 
> >> with both sides of the debate.  GM computers are terrible 
> when their 
> >> O2s fail.  And run so rich I'm couldn't understand why 
> anyone would 
> >> drive it.  Now the ECM I'm running in my Landcruiser is a 
> GM with TBI 
> >> setup out of 1989 C series 5.7l GM truck.  And it will 
> actually use 
> >> data gathered during closed loop to effect WOT.  And it can do 
> >> damage.
> >> Now, the Honda/Acura setup we're working on right now will run so 
> >> rich with the o2 disconnected it will barely idle.
> >> Now these are two cars.  I have also seen setups where you could 
> >> remove half the sensors on the car, and the computer will keep it 
> >> running like nothing ever changed.  And it won't set a 
> light.  Dodge 
> >> Caravan OBDII.  And the emissions will be perfect.  I 
> believe it is 
> >> smart enough to use other data to make a good guess (kinda like
> >> Speed-density) at what the sensor should be reading.  You would be 
> >> hard pressed to get one of these engines to hurt itself.  And if 
> >> there was misfire that could cause damage it will kill 
> cylinders to 
> >> wake the driver up (Thats if they don't see the flashing MIL lamp) 
> >> and protect the engine.
> >>      There are many computers out there, and many different 
> >> approaches used.  Now I have never personally seen a motor go boom 
> >> because of a bad o2 sensor, but I have seen a lot of damage done.  
> >> The o2 goes bad.  The cat plugs up, the exhuast is restricted, and 
> >> the temps at the engine exhuast go steadily upward.  
> Exhuast valves 
> >> damaged, seals damaged, exhuast manifolds damaged, cylinder heads 
> >> damaged.  etc,..
> >> I believe that it all depends on the computer you are using.  
> >> There are computers that go both ways....  I also don't see the 
> >> problem with an open loop car.  The Carburetor analogy is 
> a good one.  
> >> I've run vehicles 100,000 of miles with a carburetor without any 
> >> problem.
> >> And I can think of one setup or two aftermarket setups 
> that don't use
> >> o2 sensors unless you add them.  Both Eldebrock, and Holley have 
> >> aftermarket EFI setups that don't intially use an O2.  I 
> think Accel 
> >> has one two.  And these things have been used in many cars, and 
> >> trucks without any problems.
> >>     And this all started with a simple question about 
> faking out the 
> >> o2...
> >> 
> >> Marcello
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> 
> >> > I've been watching this thread over the last few days.  
> People are 
> >> > debating the safety of the stock maps with 02 faulty but 
> no one has 
> >> > mentioned that the engine in question is no longer 
> stock.  Marcello 
> >> > mentioned that his friend "only made a few changes"
> >> (eye-roll) meaning
> >> > to me that probably the friend put together a parts 
> combination far 
> >> > from stock.  Most likely higher compression and a more
> >> aggressive cam.  
> >> > Those two possibilities alone probably would make the stock maps 
> >> > irrelevant or at least "not safe".
> >> > Considering how much $$ most people typically throw at a 
> motor when 
> >> > they "make a few changes" I would proceed slowly and work
> >> to develop new maps.
> >> > I
> >> > think Marcello realizes this and hopes his friend will keep
> >> his foot
> >> > out of it until he gets home to work at the problem logically.
> >> >
> >> > My experience is with Ford EEC's.  I know when I "made a
> >> few changes" 
> >> > the EEC was totally confused because my parts changes 
> had taken the 
> >> > range of operation well beyond the stock limits of compensation.
> >> >
> >> > Good discussion.
> >> >
> >> > Dan Nicoson
> >> >
> >> >
> >> >> -----Original Message-----
> >> >> From: diy_efi-bounces at diy-efi.org 
> >> >> [mailto:diy_efi-bounces at diy-efi.org]On
> >> >> Behalf Of Steve Ravet
> >> >> Sent: Tuesday, May 31, 2005 12:36 PM
> >> >> To: diy_efi at diy-efi.org
> >> >> Subject: RE: [Diy_efi] Making a fake O2
> >> >>
> >> >>
> >> >> I was going to refer to the EFI testbench that Bruce built.  My 
> >> >> recollection is that he used a 555 type circuit to 
> generate an O2 
> >> >> signal.  There's not really any mention of it in the
> >> article, but I'm
> >> >> sure the details are in the archive.  I think for some
> >> computers this
> >> >> worked OK, for others that expected to see more
> >> correlation between
> >> >> pulsewidth and O2, it didn't.  Anyway, go to the gmecm page, 
> >> >> projects, then ECM testbench for the ascii version of the
> >> article.  
> >> >> The MS word version is probably gone for good.
> >> >>
> >> >> --steve
> >> >>
> >> >>
> >> >> ________________________________
> >> >>
> >> >>    From: diy_efi-bounces at diy-efi.org 
> >> >> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Bret 
> Levandowski
> >> >>    Sent: Sunday, May 29, 2005 11:16 AM
> >> >>    To: diy_efi at diy-efi.org
> >> >>    Subject: Re: [Diy_efi] Making a fake O2
> >> >>
> >> >>
> >> >>    Actually, it is not 'impossible to fool an ECU with a
> >> constant or
> >> >> switching voltage source'. There are two companies I know
> >> of (in the
> >> >> states) that have developed a plug-in replacement for the
> >> O2 sensor
> >> >> on numerous vehicles (mostly OBD II) that generates a
> >> 'proper' signal.
> >> >> These are used in instances where inj size was increased
> >> or a turbo
> >> >> or screw-charger was installed. Some also did require a
> >> flash of the ecu.
> >> >>
> >> >> _______________________________________________
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> >> >> Diy_efi at diy-efi.org
> >> >> http://lists.diy-efi.org/mailman/listinfo/diy_efi
> >> >>
> >> >
> >> > _______________________________________________
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> >> >
> >> 
> >> _______________________________________________
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> >> 
> >
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> 
> Regards from
> 
> 
> Mike Massen
> Perth, Western Australia
> VL Commodore Fuse Rail that wont warp or melt !
> http://niche.iinet.net.au
> 
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