As the title suggests, I'm trying to get concrete data on how inaccurate the stock wideband O2 sensor is in the Subaru Forester XT (MY06 to MY08). I am attempting to create a custom map for the car and was cautioned by a Subaru expert that the stock O2 sensor measures too rich under Wide Open Throttle, making it seem like the car is running richer that is actually the case, which in turn could be disastrous if I tried to lean out the mixture to what I think is still a safe number.

As with my previous question, I'm not after opinion (Lord knows I've had enough opinions from the NASIOC and RomRaider people). If someone can tell me e.g. "The stock Subaru O2 sensor diverges from (for example) the Innovate LC1 by 0.8 units under WOT", that would be greatly appreciated. This is just an example. I have no idea what the actual difference between the LC1 and the stock unit is.

And again, I've gotten enough opinions on the matter. What I need is hard data from someone who has measured the difference (If any).

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    To bad you didn't have an aftermarket wideband O2 you could throw in the mix to do the tuning. Would probably do you better than second hand information. Anything you get from anywhere on the net will not be exactly what you are seeing in your specific vehicle. Anything else is going to be generalized. – Pᴀᴜʟsᴛᴇʀ2 Mar 18 '15 at 16:29
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    What about turning this around? See if you can find the info for any sensor and install that one in place of the original. – jscs Mar 18 '15 at 19:09
  • I can get the aforementioned LC1 unit but because I live at the butt-end of Africa, It's going to take 6 weeks+ to get here and I'll have to pay lots and lots of import duties. I want to try and make do without it if possible. My only other option is going to a professional tuner and have him hook up his O2 sensor. But then when he asks me why, I'd have to tell him that it's because I don't want to give him money. Which would be awkward :P – Captain Kenpachi Mar 19 '15 at 8:11

I wish I could provide you with facts, I map to reality and facts are the basis of it. Alas, I cannot.

I do not believe you will have valid information unless you sample the stock 02 sensor and map output without change other than a cue of the stock 02 sensors rolling through.

The only way to determine truth regarding the matter is to buy a bunch of the sensors and measure the output of the vehicle, CO2, etc.....for each sensor. Only then can you truly determine max/mins and either corroborate or dispute claims regarding the sensor.

I wish I had more but what I've proposed is founded on the scientific method. Kindof. You just need a wider sample of data to determine 'truth'.

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    Yeah, I just wish someone else had done the tests and has the info available. – Captain Kenpachi Mar 20 '15 at 8:11
  • Indeed. It would be interesting to understand the variance in the sensor. for them it's a quality control issue. They want a tight tolerance. I have a view of Subaru that they have good quality control. When they have a higher failure rate on a component, it's tweaked pretty fast and next model years can be re-mediated. Some of the other ones (manufacturers) can have a known issue drag on for years before it's resolved. Not to be a fanboy but, unless I see some facts, I'm thinking that it's more of story line created by people that don't like Sube's thinking out loud. – DucatiKiller Mar 20 '15 at 8:31

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