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AEM UEGO Installation Questions

12502 Views 71 Replies 18 Participants Last post by  davidc44
This seems like a really straightforward thing, so I feel dumb asking this question, but I couldn't find an answer after searching.

Where do I install the AEM UEGO O2 sensor if I still have the stock downpipe?

I've got a HFC that has a bung on it for the rear O2 sensor, and I'm assuming the stock downpipe only has a bung on it for the stock O2 sensor, so where am I supposed to put the UEGO O2 sensor? Does the stock front O2 sensor get replaced with the UEGO O2 sensor and then provide "stock-like" O2 level readings for the ECU? I know I don't want the UEGO after the HFC, so the rear O2 bung is out of the question.
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get a bung welded in
noob question what happens if he replaces the rear 02?
Really?? So everyone who is installing an AEM UEGO is either going with an aftermarket downpipe or welding a bung into their stock downpipe?
noob question what happens if he replaces the rear 02?
I'll get a CEL that sticks around even if I disable the rear O2 in the ECU. I'd like to not get a CEL (hence the HFC) plus it's not good to have your wideband O2 sensor after the cat. I'm sure you don't want the stock front sensor there either, so there's really nothing to do with that bunghole (heh) except keep the rear O2 sensor there.
Really?? So everyone who is installing an AEM UEGO is either going with an aftermarket downpipe or welding a bung into their stock downpipe?
People get them welded on before they order their parts. Or the parts come with the extra bung.

What HFC do you have?
I think AEM also has a weldless bung adaptor you can use also.
Sub'd cause I'm still on stock exhaust


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People get them welded on before they order their parts. Or the parts come with the extra bung.

What HFC do you have?
I have the Cobb HFC, which only has a bung for the stock rear O2 sensor, and not enough room before the HFC for an additional bung to be welded in.

http://www.cobbtuning.com/Mitsubishi-Evo-X-SS-3-Test-Pipe-Catted-p/552202.htm
I put mine on rear o2 and disabled the rear o2 cell with accesstuner , only down fall doesn't read correctly at idle but that's it , should I re-think the placement ?

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You can weld it on the down pipe. Or upgrade to a DP with an extra bung already welded into it. I think the AMS DP has a second one already welded on.
I have the Cobb HFC, which only has a bung for the stock rear O2 sensor, and not enough room before the HFC for an additional bung to be welded in.

http://www.cobbtuning.com/Mitsubishi-Evo-X-SS-3-Test-Pipe-Catted-p/552202.htm
Ahhh, yah just get a aftermarket DP or cell the HFC an get a different one.
get a bung welded before the cat. if u drill into the cat make sure the bung is SS. But i would just weld it to the dp Make sure the bung is in a location that doesnt interfere with the flow of the air going to the first 02 sensor.
Bummer. Haven't bolted a single part to the car yet and I'm already making less $$$ and more work for myself than I planned on. That'll teach me to try to plan something! Hah
get a bung welded before the cat. if u drill into the cat make sure the bung is SS. But i would just weld it to the dp Make sure the bung is in a location that doesnt interfere with the flow of the air going to the first 02 sensor.
About how much is it to get a bung welded on?


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user from another forum said:
I removed my rear o2 and run my wideband in the rear o2 spot. It works great for me, the delay is only .1 of a sec if even that much.

^^
I think AEM also has a weldless bung adaptor you can use also.
http://www.aemelectronics.com/search/results?keywords=no+weld

About how much is it to get a bung welded on?
a bung cost me ~$3 from ebay and another $10 to the local muffler shop to weld it on (i already drilled the hole before hand). this was cheaper and imo the better route to go. getting the down pipe off the 1st time can be a huge pain in the ass though.
You can run your wideband in the rear O2 sensor bung IF and only if you are running a test pipe

thanks for clarifying :rock:
This would have been a lot easier if Cobb had moved the HFC three inches back from the flange. I understand that they wanted to have the cat as close to the turbo as possible, and they probably assumed people would just buy their dp and put the bung there, but for me it's a bit inconvenient. Oh well, no big deal.
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