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Old 08-02-2006, 09:02 AM   #1
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Modify O2 sensors

Has anyone modified their O2 sensor for more of a lean burn? If the sensor oscillates between .8 Volt(rich) and .25v(Lean) why can't you tap into it with a pot and have the voltage read a constant .3v? Will the ECU think it a fault since it's not fluctuating and trip a CEL? I guess if you have two sensors you need to modify both since the talk to each other. Thoughts?
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Old 08-02-2006, 09:10 AM   #2
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The thing about narrowband o2 sensors is that they suck. They don't really read AFRs, they just read stoich and then everything is is lean or rich. But to do this I you'd make it think it was rich so it leans itself out, thoughhhhhh I'm not a fan because I'd rather my car be knowing what's going on, because if a problem were to occur with afrs then it wouldn't be corrected properly, oh no. Not that there's really too much risk, but I'm not a fan of running leaner than the car ought to, anyway, at least not too much.

Anyway, what happened to the accord?
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Old 08-02-2006, 09:14 AM   #3
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I came across a DIY which addressed this issue. What it had, basically was a couple of op-aps set up so that when the sensor voltage got to 0.20, the output would toggle to deliver the .08 to the ecu.

From what I've read, a regular Oxygen sensor is functionally not linear when it is crossing over, it's almost more of a switch that toggles at "about" a stoic mix, but it's not calibrated, so instead of trying to read a actual value, they just keep adjusting the mix, so that it is constantly going up and down, criss crossing through stoic.

I don't think their is any reason not to do this. I don't know how much leaner it's going to go, than stock, because, my understanding is the switch point is like14:1 or 15:1, somewhere in that range. The 5 wire sensor, like is used on the HF and VX go up to somewhere in the range of 25:1, from what I've read, so even if you got the switching range tightened up, to the leaner side of the window, I don't know how much of a change we'd get.

On the other hand, with the mileage some of people are getting, it could make a bigger difference, in mileage, than it would for the average driver, on the highway.
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Old 08-02-2006, 09:21 AM   #4
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The HF doesn't use a 5 wire, but the HX does.

Anyway, normal cars don't really benefit from going lean so much. I posted up an article a while back that dyno tested leaning out the ecu on an RSX and they found the best position was 15.7:1 and that, along with timing and cam timing yielded a total of 2% FE increase,
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Old 08-02-2006, 09:26 AM   #5
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What does the HF use for an Oxygen sensor?
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Old 08-02-2006, 09:27 AM   #6
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1 wire for the win!
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Old 08-02-2006, 09:28 AM   #7
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There is a device out there for changing your o2 sensor... It is called the EFIE and you can get it at Eagle Research

http://www.eagle-research.com/products/pfuels.html

But I also think a POT would be much easier (and cheaper) to install.
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Old 08-02-2006, 09:32 AM   #8
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The accord went away. The son who did not want it decided he did. But that's good because he was driving a SUV that got 12MPG so I'm glad he has it if he'll park the tank.

Do you have a link to the DIY? I don't think that it would run much leaner the 15.1 but I think with additives and heated fuel you would see a much better increase in FE with it. I don't think you would hurt anything because if you WTO it goes to open loop and if you try to get it too lean it will go to open loop.

Inspection would be interesting I guess. I did mine last month and the guy pops the hood and is like WTF and then starts quizzing me about the VG heated fuel belly pan etc.
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Old 08-02-2006, 09:35 AM   #9
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Quote:
Originally Posted by Matt Timion
There is a device out there for changing your o2 sensor... It is called the EFIE and you can get it at Eagle Research

http://www.eagle-research.com/products/pfuels.html

But I also think a POT would be much easier (and cheaper) to install.
Thanks. I'd need 2 and that's a little to much denero for me. Plus 4-6 week for delivery.
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Old 08-02-2006, 01:52 PM   #10
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Acetone! I tried it out in the middle of summer, and for the first time ever had my coolant boil over, I decided I liked my head gasket and opted for a tow. I also saw a personal best RT of ~36mpg out of that car during the same time. I speculated that my engine was running leaner, but I wasn't sure. Then I saw a post about how acetone doesn't do anything special in the combustion chamber, but depending on your oxygen sensor catalyst, can make the ECU think you're running *richer than you are, with the result being a lean running condition. Of course this is all anecdotal, YMMV.

*I think it works by stealing atomic oxygen after the catalyst has split it, which reduces the current and the ECU thinks there's too much fuel and leans it out. Of course I'm no chemist, so who knows?
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I think if i could get that type of FE i would have no problem driving a dildo shaped car.
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