Wideband Bung: Before or After Flex Section

[Spoolin98]

I have been doing some searching and I have found that some people say weld the bung before the flex section and others say after the flex section. Some even say to install the wideband sensor in the rear 02 bung as long as you have no cat.

Where is the best place to install the sensor?

I dont have a cat, so the rear bung is a possibility. Im just not sure if its too far downstream? Is the rear bung a good place to install the sensor or no? I noticed most people put it in the downpipe.


I found this write up
http://www.dsmtuners.com/forums/art...4-how-install-02-bung-wideband-02-sensor.html

He installed it before the flex section. Also noted that he installed it on the top of the downpipe to prevent water from hitting the sensor.

I also read that you should weld the bung at a atleast a 10* angle but im not sure why? Also, from all the picture I found it seems most people just weld the bung straight on the downpipe and the sensor screws straight into the bung. Do you need a bung thats cut on a 10* angle?

 

[Twistaye]

As long as you're not right past the turbo you should be fine.. I personally have mine right after the elbow on the downpipe.. Preferably I would have done it after the flex section but I was in a hurry. Mine works fine without any issues and my GST is running better than ever now!

Not the prettiest job in the world, but it doesn't leak and that's what counts!

<a href="http://img409.imageshack.us/my.php?image=dsc00449yj2.jpg" target="_blank"><img src="http://img409.imageshack.us/img409/1498/dsc00449yj2.th.jpg" border="0" /></a>

And this is at idle.. Couldn't be happier at 14.6-14.7
<a href="http://img395.imageshack.us/my.php?image=dsc00467ce0.jpg" target="_blank"><img src="http://img395.imageshack.us/img395/3329/dsc00467ce0.th.jpg" border="0" /></a>

 

[b00stedtalon2]

On my old car it was located in between the engine and firewall next to the t-case. It was before the flex section, worked well. And you always want it on an downward angle so moisture doesn't stay on it. I had mine pointing straight down.

 

[redi4axion]

21 inches after the turbo

 

[MidnightTSI]

Just to piggyback on what everyone else is saying, I've heard that the closer the sensor is to the turbo, the more accurate it is. But at the same time, the closer it is the faster it will wear out, and the life of the sensor will be shortened dramatically. I will be installing mine before the flex section facing down

 

[BoostFrenzy]

Mount it before the flex section. Mounting it after the flex section can lead to wrong readings if you develop small leaks in the flex section. Same goes with mounting it in the rear o2 bung. It only works if you have a test pipe, and there are many places for it to leak from before the sensor and it will give you nothing but problems. Good luck on the install.

 

[crimsondragon]

Before the flex is too close to the turbo. It'll cook your sensor. I prefered to use my rear O2 sensor bung. Works well.

 

[Spoolin98]

I appreciate all the input guys...
Im getting all the same feedback as what I read, some saying before the flex and some saying after and some saying the rear 02 bung.

Im still not sure where to put it

 

[snowborder714]

Before the flex is too close to the turbo. It'll cook your sensor. I prefered to use my rear O2 sensor bung. Works well.

This will only work right if you don't have a cat, as that will mess up the wideband readings.

Im still not sure where to put it

I would say before the flex as well, mostly for the leaking flex section reason. I have mine mounted after the flex section and don't seem to have any problems. I did scrape my flex section after hitting a very nasty pothole, but I don't believe it is leaking.

So, I think either one would work. I haven't heard any horror stories from anyone mounting it in either location.

 

[nlzn]

Most Widebands come with instructions to tell you how far from the turbo to place it as well as what angle to have the bung welded on.

Basically you have two answers to your question:

The first answer is the above which is follow the directions of the wideband.
The second answer is one based upon preference (and hence why you have so many varying answers from this forum.)

As far as I go if you have to ask where to put it I think you should follow the manufacturer's instructions on placement.

 

[JayRolla]

I always install right after the downpipe bend on the top. Works out great.

Also for the people saying your sensor will die are wrong. My brother has ran his wbo2 in the stock o2 location on the o2 housing for over a year with no issues. It may die faster but it wont just burn up.

 

[Spoolin98]

Thanks for the input guys, I think im going to install the bung right before the flex section on the top of the downpipe and call it a day.

 

[Spoolin98]

Well I ended up installing the 02 sensor in the rear 02 sensor bung. My buscher downpipe has the flex section right after the oil pan so there was no way for me to install it right before flex section because the oil pan was in the way. I thought about welding the bung in after the flex section, but in that case I figured I mind as well just put it in the rear bung and save myself some trouble. Either way its after the flex section which may leak, so I took the easy route.
Its working fine as far as I can tell.
Thanks again for the input guys.

 

[1992awdlaser]

It won't be anymore or less accurate because of it's position. It can be placed at the end of the exhaust and it will still be as accurate as if it were placed right after the turbo. The difference is the further away it is, the longer it will take to react. The only reason the manufacturer recommends it be placed a certain distance after the turbo is to keep the sensor from going bad too quickly.

If you can easily run the wiring, I would mount it before the flex section. The reason I would do this is to prevent spots where exhaust leaks can happen in front of the sensor. If you put it after the flex section, there is a good chance it will be thrown off by an exhaust leak sometime in the future. The flex sections have a tendency to get leaks. With it before the flex section, there are minimal spots between it and the engine that can get exhaust leaks.

 

[cali]

As long as you're not right past the turbo you should be fine.. I personally have mine right after the elbow on the downpipe.. Preferably I would have done it after the flex section but I was in a hurry. Mine works fine without any issues and my GST is running better than ever now!

Not the prettiest job in the world, but it doesn't leak and that's what counts!

<a href="http://img409.imageshack.us/my.php?image=dsc00449yj2.jpg" target="_blank"><img src="http://img409.imageshack.us/img409/1498/dsc00449yj2.th.jpg" border="0" /></a>

And this is at idle.. Couldn't be happier at 14.6-14.7
<a href="http://img395.imageshack.us/my.php?image=dsc00467ce0.jpg" target="_blank"><img src="http://img395.imageshack.us/img395/3329/dsc00467ce0.th.jpg" border="0" /></a>

every wb install i've seen says to install it here.

 

[Spoolin98]

Well I installed it in the rear bung for now. In the future when I have the downpipe off for some reason maybe Ill move it up front.
The only way I could install it before the flex section is on the side of the downpipe like the previous poster showed a picture of. I wanted to install it in the top of the downpipe so the sensor would screw down into it, but I couldnt. So for now im just going to keep it in the rear 02 bung.

 

[snowborder714]

If I remember correctly, it's better to mount the wideband between 10 and 2 if you relate a clock face to the pipe.

 

[Spoolin98]

If I remember correctly, it's better to mount the wideband between 10 and 2 if you relate a clock face to the pipe.

I dont recall reading that anywhere but if I were to move the wideband I would put it in the 10 location because thats the only way I could put it without interference.

 

[mitsu-luver]

most o2 sensors operate best at about 800*, i don't know exactly where that temp occurs at but i thought it might help
i always see guys mount there sensor like 12" down after the turbine outlet.

 

[Anarchology]

I would have to say that mine is on my 3" downpipe right near the axel. I don't see how having it that far down could be any problem given the O2 is heated and there are no breaks allowing any air to escape or enter before that point.

I would probably suggest putting it anywhere the pipe is straight rather than on an elbow, so you tap into the straight flow. That may be just another thing that doesn't matter as well.