Fooling Oxegen Sensor Output - Fuelly Forums

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Old 05-30-2011, 02:57 AM   #1
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Fooling Oxegen Sensor Output

WOULD LIKE TO SEE IF ANYONE WITH ELECTRONICS EXPERIENCE CAN HELP

read about diode reducing ox sensor reading by about 500 mv which someone was using to fool post cat o2 sensors to get rid of check engine light

but i was thinking if i used the diode and then wired a 650-700 mv rechargable battery i could fool the computer to thinking the engine was always running a little rich

i haven t tried it yet , but it seems to make sense , just like when you wire two twelve volt batteries in line to get 24 volts

the battery i think would raise the voltage when the engine was lean , making it a little leaner and charge when the engine cycles to rich ,and also make it a think it was alittle richer

and if you wire in a bypass ( three way switch ) before the diode you would run stock , and after the diode you could run rich if you were trying to get somewhere fast , and use the battery to save gas

will someone with a little more technical knowledge please get back to me on this ,, if ther is something i am missing or need a special battery to keep it from overheating?

but i an pretty sure since the reading would only be off by 100mv or so it would not even make the light come on
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Old 05-30-2011, 03:07 AM   #2
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Re: Fooling Oxegen Sensor Output

i think the main concern would be to find a battery that doesnt overheat

or use a bigger battery and some kind of resistor , but any added resistance would maybe make the check engine light come on

how much resistance is in a battery?

or you could start engine in stock mode and then switch to battery after it is in closed loop mode and checks by pcm are already made
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Old 05-30-2011, 03:46 AM   #3
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Re: Fooling Oxegen Sensor Output

Search the site for EFIE. That's what the device you're describing is usually called. You should be able to find some plans for making one.
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Old 05-30-2011, 07:07 AM   #4
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Re: Fooling Oxegen Sensor Output

On a related note, when I was looking for parts for my motorcycle, I noticed a wide band O2 sensor upgrade kit available for 2007 & up Harleys. What was intriguing about it was that it included a computer unit. You could program the computer unit for whatever fuel mix you wanted (up to 20:1 I believe), and when that target was reached it would report 14.7:1 to the vehicle's on board computer.
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Old 05-30-2011, 07:33 AM   #5
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Re: Fooling Oxegen Sensor Output

That sounds like something that could be adapted for other applications...how much do they charge for it?
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Old 05-30-2011, 08:39 AM   #6
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Re: Fooling Oxegen Sensor Output

I don't remember... I'll have to see if I can find it again.
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Old 05-30-2011, 08:50 AM   #7
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Re: Fooling Oxegen Sensor Output

This is the page I saw it on, but there doesn't seem to be a price.

http://www.nightrider.com/biketech/h...o2_upgrade.htm
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Old 05-30-2011, 09:04 AM   #8
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Re: Fooling Oxegen Sensor Output

Found some DIY O2 sensor adjusting info there:
http://www.nightrider.com/biketech/h...olt_divide.htm

They have info for making it rich but it probably can be used to go the other way.

Of course, when messing with O2 sensor output to make the engine run lean, you have to be careful not to damage or destroy your engine with your lean mixture.
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Old 05-30-2011, 01:15 PM   #9
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Re: Fooling Oxegen Sensor Output

Here's a link to a low cost EFIE. I tried one a couple years ago, but it didn't seem to help any. I monitored the 02 signal using a DMM and all I saw was the ECU bringing the reading back the target voltage. The target voltage for the 02 sensor is in the .45-.50 range and it seems that adding the voltage to the reading didn't keep the ECU from adjusting it back to the target voltage. I also suspect if you added enough voltage that the ECU couldn't make the necessary corrections the 02 sensor reading would kick you into open loop operation. This was my experience on one of my cars, the results may be different for other vehicles.

http://www.youtube.com/watch?v=PEHJ9te7gvk
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Old 05-30-2011, 05:28 PM   #10
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Re: Fooling Oxegen Sensor Output

the pcm will keep it running in what it thinks is that range
but if there is voltage of say 100 mv added you will only see it for a second or two , then the computer will lean the mixture and bring voltage back into range
only the fuel mix will be lean
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