Modify O2 sensors

[zpiloto]

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?

[SVOboy]

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?

[Gary Palmer]

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.

[SVOboy]

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,

[Gary Palmer]

What does the HF use for an Oxygen sensor?

[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.

[zpiloto]

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.

[diamondlarry]

Originally Posted by zpiloto

Thanks. I'd need 2 and that's a little to much denero for me. Plus 4-6 week for delivery.

Eagle Research tries to say that you need 2 EFIE's but you only need 1. I found that out several years ago. Fran Giroux and I figured out that the only thing the rear sensor does is verify that the cat is working. Therfore, as long as the rear sensor sees a smaller voltage, the ECU is cool. The front sensor is the only one that controls the mixture so it's the only one you need an EFIE for. Plus, you save $50.

[ZugyNA]

http://www.lubedev.com/smartgas/ultra5.htm


Cover Oxygen Sensors with Aluminum Foil: Wrap your oxygen sensors in the exhaust pipe with 7 to 10 layers of shiny foil.

Advantage: The car computer system depends on the oxygen sensors to adjust the air-fuel mixture being fed to the engine. The cooler the exhaust gases, more fuel gets sent to the engine. The hotter the exhaust gases and the oxygen sensor, less fuel will be sent to the engine.

Directions: To seal maximum warmth inside the area near the sensor, insulation in the form of Reynolds Aluminum Foil is employed to insulate the oxygen sensor. Wrap five inches in front and five inches after the sensor to keep it warmer. We double a one-foot section of foil and wrap that around the pipe and around the sensor itself. Do not remove the sensor. Then we repeat the process several more times. Finally we use .030" copper or aluminum wire to wind around the aluminum foil to keep it from blowing away and be sealed against water. The wire comes from any welding supply. The goal is to fool the car's narrow band sensor and computer into sensing too rich a mixture so it adjusts to a slightly leaner mixture and possibly a slight advance in timing. The end result is smoother engine operation and better MPG. This trick is especially important in severe winter climates. My catalytic converter went bad after 147,000 miles. A large piece inside was blocking the exhaust flow and cost me a drop of 12 MPG. I replaced both oxygen sensors and the catcon and wrapped the sensors with aluminum foil so my MPG came back. Do not wrap with ordinary gray duct tape as it will burn off. Have your mechanic CHECK that catcon on your car. Do not take it for granted because all the good changes you make for mileage could be negated by such things as a bad catcon or bad plug wires or bad oxygen sensors some such hidden defect.

I'm pretty sure that adding resistance to the O2 output makes the mix richer. I have an EFIE the V6...helps some.

[zpiloto]

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.