what does this mean?

[pantswagen]

http://bbs.scoobynet.com/general-technical-10/696426-wideband-afr.html

[split_trix]

they are talking about a wideband o2 sensor..... have a look at innovate lc-1..

its a way of Knowing your Air/Fuel Ratio - all the time.. especially on forced induction engines.

vw speeshop sell them
http://www.vwspeedshop.com/store/home.php?cat=420

chris
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52 vwrx

[CycloneMike]

A narrowband lambda can basically only tell you (or your ECU) that your engine is running rich, lean or at a stoichiometric air fuel ratio.
A wideband gives an acurate usable AFR value often in the range AFR = 10-20:1. (stoich = 14.7:1)
So why would I need one?
Perhaps to put a gauge on your dash to show what AFR your engine is running at. Could be useful if you have made mods and not correctly reset the fuelling, then you will be able to see exactly how week your engine is running whilst you drive and therefore how soon it will be damaged. Particularly useful with turbo engines where due to too much boost mixture can easily be made lean. This will be in addition to the the NB that your ecu will still require.
If you have a mappable ECU a WB can be used to set up the ECU.
The real use is when a WB is linked to an ECU that is capable of using the info to alter the fuelling live. Then the ECU can adjust the fuelling dependant on the driving at that time. ie run lean for ecconomy when cruising on the M6 or run rich for power when baiting chavs etc.
You can't normally just swap a NB for a WB and then get a benifit. They work with a controller which is a box that interprets the signal and provides a usable output this is the LC1 part that is refered to. The actual WB itself doesn't look much different to a NB and can be sourced from some later production cars, who's ecus were designed to use them.
So in summary, not required unless you have the kit to make some use of it.
If you have a few spare weeks/months look up megasquirt. Ignore the bit about building it and jump to the tuning theory stuff.
Sorry its not Subaru specific or gospel, just my understanding and interpretation of how it works. Hope it helps.