orikosan

I am going to get a UTEC plus XS Tuner and from what I understand the tuner will come with an O2 bung for the wideband sensor.

I gather from reading various posts that the best place for attaching the wideband sensor is in the downpipe ? Could someone confirm this for me ? If this is so where should I have the bung welded to ?

Also how effective would the wideband sensor be if placed AFTER the cat ? Anybody know if the wideband reads different values before and after the cat ? If so by how much will the reading differ ?

If it's the case that the WB O2 should really be in the downpipe, I am thinking of buying an aftermarket downpipe now, and then a cat back system later.
I believe most 3" downpipes will still hook up to the stock cat. Can anybody confirm or deny this ?

Finally does anybody have any recommendations for downpipes ??

nothere

iTrader: (23)

I think the latest shipment of tanabe downpipes have a bung in them, check them out. 2.75" pipe. if you are going to live with the stock cat you don't need a 3 " downpipe, unless you want it, ( they are cheaper , because that is what everyone gets.)otherwise just have one put on the downpipe of your choice. the bung needs to be before the cat. after the cat the readings will not be any use to the tuner.

MalibuJack

iTrader: (5)

I use the Buschur downpipe, I put my O2 bung just after the elbow, which works out well, its easy to access from under the car, but real close to the stock location (under 8" away)

Don't bother with putting it after the CAT.. you will not get good readings with it. The closer to the o2 housing the better.

PDXEvo

iTrader: (4)

According to several items I have read you want the 02 sensor located in your downpipe before the CAT but no to far away from it as the gasses will be too hot and you will not get accurate measurements. If my memory recalls this properly I believe the O2 sensor uses an internal heater to heat up to 750 degrees and requires the gas to be under 400 degrees. Dont forget to perform a free air calibration before hooking it up though! You can get a lot of really good information on this from TurboXS' web page!

nothere

iTrader: (23)

the inovative people have a fitting that insolates the 02 sensor from extreme heat, in case you have the bung to close.
http://www.innovatemotorsports.com/x...me.php?cat=250

MalibuJack

iTrader: (5)

As long as its in the downpipe and before the CAT it'll work fine.. Even if its close to the Stock O2 housing you won't have any problem with it. the temps in that area don't get hotter than its "Operating" temp... Before the turbo is another story and certainly not recommended.

propellerhead

iTrader: (3)

I'm sure the WBO2 sensor will work fine anywhere between the stock O2 sensor location and before the cat. However, according to AEM and Innovative Motorsports, sensor life is a function of how hot the operating environment of the sensor is. Exposure to the higher temps found at or just after the O2 housing supposedly greatly reduce sensor life. I'm having my bung welded as far downstream as I possibly can just before the cat.

MalibuJack

iTrader: (5)

BTW, once its about 8 or so inches passed the turbo, its cool enough not to damage it if its a concern..

orikosan

I originally started this thread about where to place the Wideband O2 sensor, and everyone's opinion seems to be forget about placing it after the cat because you just won't get any reliable readings.

If that is so, how do "road tuners" do it ? When I witnessed one road tuner I saw them jack up the passenger side of the car, and go under the car from under the passenger side door. The only place that they could put an O2 sensor by going under the car from there would be by removing the stock O2 sensor after the CAT and putting in their wideband AFTER the CAT.

So does this mean any cars tuned by this method are totally out of wack ???

marksae

iTrader: (12)

Maybe that guy had a test pipe on his car?

orikosan

No, everybody was running cats.

MalibuJack

iTrader: (5)

You will still get AFR readings, but their nowhere near as accurate as placing it ahead of the cat.. at WOT the catalytic converter does very little to clean the emissions therefore you can still get a reading..

the catalytic converter really only does its job when the car is in closed loop operation.. simply because the airflow through it and the mixture is close to 14.7 (stoichiometric ratio, or the theoretical perfect ratio of air to fuel)

under heavy load and WOT, the flow through the catalytic converter isn't "Scrubbed" like it is..

So the simple answer is "YES" Its possible to measure it that way, however its not as accurate and this has to be taken into account when tuning.