Question about O2 Sensor mods
 

I recently bought a 2003 Ford Expedition which we use for camping trips. The mileage is not bad for a 5,600 pound vehicle but it could definitely be better. I know it needs new O2 sensors since the previous owner had the worst maintenance I've ever seen. On my laptop the O2 sensors are very slow reacting unless your cruising on the highway, but at low speeds they aren't hot enough or something and they don't give good readings like new sensors. They have 139,000 miles on them.

When I replace them, I'm thinking of working with them a little bit to peak out the mixture slightly more. I have a dual EFIE box that I used on my explorer.

My question first is: Does higher voltage from the O2 mean leaner or richer? Also I know it's a 4 wire heated sensor, but what "Type" is it? I keep reading about zirconia and planar and some other types that either create their own voltage or use a reference voltage. But so I understand it better, I need to know what type I have.

I've read one article saying to wrap the O2 sensor and surrounding pipe with tin foil and heat wrap, to make it hotter which supposedly tells it to give less fuel. (sounds backwards to me) Then I read another article saying to use spark plug anti-fouler to extend the O2 sensor away from the pipe causing it to be cooler, which they say tells the computer to burn less fuel..... the two articles completely contradict each other.

Re: Question about O2 Sensor mods
 

It doesn't have to do with heat. (At least not as I understand it) The goal of wrapping in foil, or using a drilled out spark plug anti-foul adapter is to take the O2 sensor out of the main stream of exhaust, and it will read on the rich side, which will make the computer lean out the fuel injectors.

Re: Question about O2 Sensor mods
 

I think the sensor just needs heat to operate. Which is why a car, at start up, is in open loop, the oxygen sensor hasn't heated up yet.

I've read, you can check the senor, when removed, by hooking it up to a volt meter and heating the tip with torch. It should produce a current.

Re: Question about O2 Sensor mods
 

It's a heated sensor so it's supposed to be ready to operate within 10-20 seconds. But besides that, the hotter it is, the more quickly it reacts to changes in oxygen content which causes the high/low voltage reading that constantly oscillates. Mine are operating kind of slow which means normally that they're due for replacements.

My question was more about what style does the 2003 model have in it? Some sensors alternate a small amount of current feedback to the computer, and some sensors alternate just the voltage, and then there's also the wideband type. I don't know which style is in use for 2003 Ford OBDII.

Also, I'm trying to understand how wrapping tinfoil around the sensor is supposed to make the vehicle run leaner. It's going to make it hotter and possibly more accurate, but leaner also? Has this actually been proven?

Re: Question about O2 Sensor mods
 

I've tried wrapping the 02 sensor with foil and adding a spark plug anti fouler to get the sensor out of the exhaust stream. When I wrapped it with foil my mileage dropped and when I used the anti fouler it stayed about the same. This is just my experience, your results may be different.

Re: Question about O2 Sensor mods
 

I'm sure that wrapping an O2 sensor will impair its ability to function.
It needs contact with air as well as with exhaust gases.