[WolfPlayer]

Finally got around to collecting a bunch of data that illustrates how inaccurate the stock narrow band O2 sensor is. I did this for n00bs who don't know any better. This post will come in 'handy' in other forums here at IWSTI. I collected a lot of part throttle data with the LC-1 Wideband vs. the Stock O2 Sensor AFR (I also graphed boost). The X-Axis is time. The left Y-Axis is AFR. The right Y-Axis is Boost (psi). 17 graphs in this directory that clearly illustrate how inaccurate the stock O2 sensor is. I can't imagine anyone even trying to tune based on this data. Feel free to pass this post around when someone talks about tuning off the stock O2 sensor. Egad.

17 graphs and the actual XLS file.
http://www.bescaredracing.com/sti/data/nb_vs_wb/

Here are a couple quick examples but I would recommend looking at all of them ...





t

[1FastSTi]

I was expecting them to be alot worse then what they accually are. Good post none the less.

[WolfPlayer]

Originally Posted by 1FastSTi

I was expecting them to be alot worse then what they accually are. Good post none the less.

12.2 on my wideband is around 11.1 on the stock narrowband. That's huge in my book ... enough to destroy the motor.

t

[1FastSTi]

Originally Posted by WolfPlayer

12.2 on my wideband is around 11.1 on the stock narrowband. That's huge in my book ... enough to destroy the motor.

t

Absolutely. I agree 100%, I guess I say that because in my book I wouldn't even consider the stock NB even any kind of tuning tool. Its good enough for the stock ECU to operate properly on unmoddified engines. It was really only designed to read stoichiometric and thats really all its doing.

[Nixlimited]

Hey wolfplayer, where do you have your wb tapped into? Up-pipe?

[WolfPlayer]

Originally Posted by Nixlimited

Hey wolfplayer, where do you have your wb tapped into? Up-pipe?

Nope. Mine is in the downpipe about 4" after the turbo but before the cat. I did give some thought to how pressure might be affecting the stock O2. That is why all of these tests are at part throttle. Anybody know at what pressure a stock narrowband will start deviating from expected values? Also, for the record, the pressure produced in the uppipe is why you NEVER want to put a wideband in the uppipe. The pressure will distort the readings.

t

[Nixlimited]

Originally Posted by WolfPlayer

Nope. Mine is in the downpipe about 4" after the turbo but before the cat. I did give some thought to how pressure might be affecting the stock O2. That is why all of these tests are at part throttle. Anybody know at what pressure a stock narrowband will start deviating from expected values? Also, for the record, the pressure produced in the uppipe is why you NEVER want to put a wideband in the uppipe. The pressure will distort the readings.

t

Well, I have an APS exhaust with a cat immediately following the turbo. Where on my car should I consider installing the wideband?

[WolfPlayer]

If you check my signature you will see that I have an APS exhaust with cat too Put it in the bung in the downpipe. You can see my wideband clearly in this pic on my site ...

http://www.bescaredracing.com/sti/wi...l/DSC04796.JPG

t

[Nixlimited]

Originally Posted by WolfPlayer

If you check my signature you will see that I have an APS exhaust with cat too Put it in the bung in the downpipe. You can see my wideband clearly in this pic on my site ...

http://www.bescaredracing.com/sti/wi...l/DSC04796.JPG

t

Sweet, there is already a bung!

[WRX_XB9R]

My Cobb DP also has a bung about 6" from the turbo. No problems so far.

[1FastSTi]

Hey WolfPlayer do you keep your wideband in all the time? If so, how long do they usually last?

[WolfPlayer]

Originally Posted by 1FastSTi

Hey WolfPlayer do you keep your wideband in all the time? If so, how long do they usually last?

Yup - all the time. I'll let you know how long it lasts when it dies - lol. It's been running fine for the last 4 months full time. (~3000 miles). With the research I did ... I am expecting 20,000 miles at least. They are only $36 + shipping for a new sensor (and I have a spare) so I am not worried about maintenance on this item. I enjoy being able to log whenever I want without worrying about putting a sensor in (even though it is really easy) ... I'm lazy like that Plus, soon I will have the innovate motorsports XD-1 gauge so that I can always see the AFR - might as well install the gauge since my WB is in all the time.

t

[MidlifeCrisis]

Mine is in all the time and in the same place. Does anyone have a sense of how long the delay is from the combustion chamber to the turbine outlet?

I realize it is a function of a lot of variables, but any rule of thumb would be interesting to hear. I have always wondered if I should skew the WB column in my logs by a few rows to make it more immeidately representative of the other data being logged in any partiuclar record.

[Nixlimited]

Originally Posted by MidlifeCrisis

Mine is in all the time and in the same place. Does anyone have a sense of how long the delay is from the combustion chamber to the turbine outlet?

I realize it is a function of a lot of variables, but any rule of thumb would be interesting to hear. I have always wondered if I should skew the WB column in my logs by a few rows to make it more immeidately representative of the other data being logged in any partiuclar record.

I am guessing an extremely short period of time. Just think about the MAF reading and tuning, it would have the same offset problem.

[MidlifeCrisis]

Good point. Now I'm wondering what the transit time from MAF to turbine outlet is, particularly with my FMIC plumbing in there. Sorry, Wolf, not trying to hijack the thread.