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Old 10-02-2012, 04:54 PM   #1
RoadKillDMD
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Default Bad Spot For O2 Sensor?

I'm in the process of installing my AEM UEGO gauge and have a quick question. The instructions state to have the bung welded in at least 36" downstream from the exhaust port. I found a place where I can mount the sensor and have plenty of space so it doesn't get hung up anywhere.

My question is, I marked the spot in the pictures below, will the sensor being mounted on that bend cause any problems with the gauges accuracy?







Any input would be appreciated. Thanks!

DMD
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Old 10-02-2012, 06:05 PM   #2
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probably going to hit the bottom of your car there. Going to need to put it closer to the seam where the cast and stainless meet facing the trans. COBBs version of that dp has it right at the top after the turbo. I have my uego about 12 inches max from the turbo, right were my tuner wanted it.
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Old 10-02-2012, 06:10 PM   #3
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"36" downstream from the exhaust port" doesn't mean "36" downstream from the turbo". You also have to count turbo and length of the uppipe and headers.
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Old 10-02-2012, 06:55 PM   #4
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Quote:
Originally Posted by scby rex
probably going to hit the bottom of your car there. Going to need to put it closer to the seam where the cast and stainless meet facing the trans. COBBs version of that dp has it right at the top after the turbo. I have my uego about 12 inches max from the turbo, right were my tuner wanted it.
It won't hit anything, I'm sure of it I chose this spot while the DP was still on the car to make sure the sensore wasn't going to hit the firewall or any crossmembers when I install it. There's plenty of room. I just want to know if the sensors accuracy will be compromised if it was mounted at that bend. Will the bend cause any change in exhaust flow to the sensor causing it to misread?

Quote:
Originally Posted by kaczmarz
"36" downstream from the exhaust port" doesn't mean "36" downstream from the turbo". You also have to count turbo and length of the uppipe and headers.
36" psshhh I took all of that into account, thanks . If you look again, my mark is only ~18" from the turbo flange ...
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Old 10-02-2012, 07:09 PM   #5
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Quote:
Originally Posted by RoadKillDMD View Post
It won't hit anything, I'm sure of it I chose this spot while the DP was still on the car to make sure the sensore wasn't going to hit the firewall or any crossmembers when I install it. There's plenty of room. I just want to know if the sensors accuracy will be compromised if it was mounted at that bend. Will the bend cause any change in exhaust flow to the sensor causing it to misread?



36" psshhh I took all of that into account, thanks . If you look again, my mark is only ~18" from the turbo flange ...
dont be a fool. put the sensor up closer to the turbo.
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Old 10-02-2012, 08:25 PM   #6
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Quote:
Originally Posted by Black94Snake

dont be a fool. put the sensor up closer to the turbo.
So, I'm a fool for following instructions? Well you're no help at all!

Just to be clear, I plan on using this gauge to constantly monitor my AFR's and I don't want to have to replace the sensor more than I need to. I've heard of people running this sensor just past the turbo and being fine for over a year. On the other hand, I have also seen that plenty of sensors were crapping out within the first couple of months at this location... I want to play it safe and install the sensor where and how it describes in the instructions.
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Old 10-02-2012, 08:30 PM   #7
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putting your WBO2 that far downstream will skew any results you have when trying to tune. Especially because of the location of those bends. putting it closer to the turbo WONT hurt it, and will make it more accurate.


But one has to ask, why are you even bothering to ask the question when you are just going to ignore the input from those who have CLEARLY been doing this MUCH longer than you.

Do you think so many aftermarket DP makers would put an O2 bung in the bellmouth if it was a bad idea to run the sensor there? (cobb for example)


At the end of the day, its your car, so I could give a flying **** if you go run it into a wall. I just think you need to pull your head out of your ass and try listening to the experience people on this forum.
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Old 10-02-2012, 09:01 PM   #8
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I have EL Perrin headers and they have 16-18" long tube for each head and about 6" for each pair of heads. Then add 12" for uppipe and you have almost 36" of piping before turbo!

I know the lengths well because I had to pre-cut the wrap before wrapping the heads and uppipe.
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Old 10-02-2012, 09:11 PM   #9
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uhhhhhh.... i have mine further down from that based on what my tuner suggested. he said... "dont put it up in the bellmouth, ive seen cars have some funny readings with it mounted there" .....it is about 12" up from the stock sensor, on the right hand side of the car at about a 15 deg angle up. there is a little space between the downpipe and the frame.
works great. ill try to get some pics.


Now, if you think about it from an "gas flow" perspective.. at wot, the velocity in the turbine side of the belmouth is fast and the wg side is turbulant... this means any swirling gases on that side would go lean/rich/lean... depending on how the gases were moving. It would make beter since to get it down in the main stream of the gases away from this to give a more consistant reading.

the graphs from my aem failsafe, looking at the af's... look smooth.
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Old 10-02-2012, 10:22 PM   #10
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Quote:
Originally Posted by hutch959
uhhhhhh.... i have mine further down from that based on what my tuner suggested. he said... "dont put it up in the bellmouth, ive seen cars have some funny readings with it mounted there" .....it is about 12" up from the stock sensor, on the right hand side of the car at about a 15 deg angle up. there is a little space between the downpipe and the frame.
works great. ill try to get some pics.

Now, if you think about it from an "gas flow" perspective.. at wot, the velocity in the turbine side of the belmouth is fast and the wg side is turbulant... this means any swirling gases on that side would go lean/rich/lean... depending on how the gases were moving. It would make beter since to get it down in the main stream of the gases away from this to give a more consistant reading.

the graphs from my aem failsafe, looking at the af's... look smooth.
It's the same exhaust coming through the turbine and the wastegate...
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Old 10-02-2012, 10:37 PM   #11
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Quote:
Originally Posted by Black94Snake
putting your WBO2 that far downstream will skew any results you have when trying to tune. Especially because of the location of those bends. putting it closer to the turbo WONT hurt it, and will make it more accurate.
Post cat or after an exhaust leak maybe... Unless you have a plot showing WOT AFR readings at different locations on a catless exhaust, GTFO. There are many people running widebands in the stock rear O2 bung. Why would instructions tell you to mount it farther down if it was going to skew the readings?

Quote:
Originally Posted by Black94Snake
But one has to ask, why are you even bothering to ask the question when you are just going to ignore the input from those who have CLEARLY been doing this MUCH longer than you.
Like you? >>"PUT IT CLOSER TO THE TURBO! " Yeah, super informative br0! If you have some real input, please do share. Otherwise, please don't waist my time...

Quote:
Originally Posted by Black94Snake
Do you think so many aftermarket DP makers would put an O2 bung in the bellmouth if it was a bad idea to run the sensor there? (cobb for example)
Those bungs are meant for widebands to be TEMPORARILY mounted for tuning purposes. Heat kills the sensors. The closer to the heat source, the faster your o2 sensor will dye. FWIW, I have read instructions clearly stating that 'Even though the DP has an included bung 4" post turbo, it shouldn't be used as the sensor will overheat under boost.'

Page 2, sect. 4
www.wbo2.com/lsu/lsuinstal.pdf

Quote:
Originally Posted by Black94Snake
At the end of the day, its your car, so I could give a flying **** if you go run it into a wall. I just think you need to pull your head out of your ass and try listening to the experience people on this forum.
Now that's just plain rude...

Last edited by RoadKillDMD; 10-02-2012 at 10:45 PM.
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Old 10-02-2012, 11:01 PM   #12
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Dont put the sensor in the bend of any tubing (creates a weak point). Bottom out once on a speed bump and you will be very mad. Not only that, but from experience that is too close still. I know what the directions say, but move it further back about another 6" to 8". Ive installed many of these and most pro tuners will tell you this is where to install it also.
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Old 10-02-2012, 11:44 PM   #13
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Quote:
Originally Posted by UK-Wagon
Dont put the sensor in the bend of any tubing (creates a weak point). Bottom out once on a speed bump and you will be very mad. Not only that, but from experience that is too close still. I know what the directions say, but move it further back about another 6" to 8". Ive installed many of these and most pro tuners will tell you this is where to install it also.
Finally! Just the response that I needed. Thanks a lot UK-Wagon!
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Old 10-03-2012, 03:47 AM   #14
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Quote:
Originally Posted by UK-Wagon
Dont put the sensor in the bend of any tubing (creates a weak point). Bottom out once on a speed bump and you will be very mad. Not only that, but from experience that is too close still. I know what the directions say, but move it further back about another 6" to 8". Ive installed many of these and most pro tuners will tell you this is where to install it also.
I'm with this dude . 6 to 8 will be good on my 2012 WRX I have my wideband tig welded 2 1/2 inches before the stock o2 sensor
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Old 10-03-2012, 06:48 AM   #15
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This may not be what you are looking for but here goes:

I've been here since Lincoln was in office. I've seen them used and installed from every clock position from 1 to midnight and back again. I've seen them used and installed from every pipe position from 2 microns from the turbo to hanging out of the tailpipe. In the grand scheme of things, it matters not where you install the damn thing. Install it where you think would be best and provides easiest access if you are going to be futzing with it a lot. Then have yourself a cup of tea and a cigarette on one of those long cigarette holders you see women in the 20s use.
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Old 10-03-2012, 08:10 AM   #16
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Quote:
Originally Posted by RoadKillDMD View Post
I'm in the process of installing my AEM UEGO gauge and have a quick question. The instructions state to have the bung welded in at least 36" downstream from the exhaust port. I found a place where I can mount the sensor and have plenty of space so it doesn't get hung up anywhere.

My question is, I marked the spot in the pictures below, will the sensor being mounted on that bend cause any problems with the gauges accuracy?







Any input would be appreciated. Thanks!

DMD
yer gunna do whatever yer gunna do with it regardless of what anybody tells you

so just bloody install it and stop wasting our time here
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Old 10-03-2012, 12:43 PM   #17
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Quote:
Originally Posted by Uncle Scotty

yer gunna do whatever yer gunna do with it regardless of what anybody tells you

so just bloody install it and stop wasting our time here
I'm pretty sure I aggreed with UK-Wagon about moving it, but okay

Quote:
Originally Posted by Unabomber
This may not be what you are looking for but here goes:

I've been here since Lincoln was in office. I've seen them used and installed from every clock position from 1 to midnight and back again. I've seen them used and installed from every pipe position from 2 microns from the turbo to hanging out of the tailpipe. In the grand scheme of things, it matters not where you install the damn thing. Install it where you think would be best and provides easiest access if you are going to be futzing with it a lot. Then have yourself a cup of tea and a cigarette on one of those long cigarette holders you see women in the 20s use.
Thanks Bomber. That actually does help a lot!

I'm all done with this thread mods if ya feel like locking it
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Old 10-03-2012, 12:53 PM   #18
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Remember, the farther downstream your wideband is, the greater the lag between combustion and the readings. A big lag can make tuning your fueling an absolute nightmare, especially under WOT or dynamic conditions (tip-in, etc).

With the sensor down by the stock rear one, I wouldn't be surprised if you have a 1/4 second delay between combustion and measurement. At the CAN logging speeds of what, 100 Hz? You're going to need to look 20-30 lines down in your log to find the AFR that corresponds with a given load/MAF/RPM. At low load the delay will be even larger.
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Old 10-03-2012, 12:59 PM   #19
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Quote:
Originally Posted by the suicidal eggroll
Remember, the farther downstream your wideband is, the greater the lag between combustion and the readings. A big lag can make tuning your fueling an absolute nightmare, especially under WOT or dynamic conditions (tip-in, etc).
How far back would you suggest is too far? I didn't plan on going as far back as the rear o2 sensor. I was going to follow UK's advice and move it bak just a few more inches from where my mark is now.
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Old 10-03-2012, 01:10 PM   #20
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There's no real "this is too far" line, the correlation will just get worse as you go farther back. My sensor is about 8" from the turbo and I already have a lag of about 170 milliseconds (best guess by doing multiple WOT logs in different gears and cross-correlating the AFR error vs RPM in each log for different lags).
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Old 10-03-2012, 01:14 PM   #21
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Makes sense. Thanks for the input Eggroll! I'm off to the muffler shop
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Old 10-03-2012, 06:49 PM   #22
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hopefully your "muffler shop" isnt going to make it look like bird **** with mig welding splatter.
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Old 10-03-2012, 07:21 PM   #23
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Mine is way the f back almost at the cat back. It reads just fine. Turboxs put it there on their down pipe
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