O2 sensor and wideband placement.

[Perkul8r]

I am gonna have the muffler shop weld in a 2nd o2 sensor bung, and a bung for my wideband. But i am not sure where to place them. The DP i am using only has one bung installed and its closer to the back. I was thinking that one would work for the wideband. But than that leaves me the 2 o2 sensors. Thanks for any help.

Here is the DP i am using.
The car is a 1998 Legacy with the 2.2 NA motor.
https://sl-i.net/FORUM/

[Robbks]

What year is the engine?

I agree, use the rear bung for the wideband
put your primary o2 sensor in a bung about 6" past the top bend in the dump-pipe (factory location MY99 JDM WRX)

what are the factory locations for the two sensors (AUDM cars don;t have as many o2 sensors as USDM cars for some reason)

[Perkul8r]

Well, i have 2 o2 sensors casue my car is a 98. So its obd2. And the factory 2 positions are one before and after the cat. I am going catless with this project, no emissions testing what-so-ever here. lol.

[Robbks]

(from factory) is there a cat in the up-pipe aswell as the one in the dump-pipe?
or are both o2 sensors post-turbo..?

I know the AUDM (~01) cars have 2x o2 sensors
one is in the exhaust headers before the up-pipe
there is then a second one in the exhaust after the front cat converter (about level with the drivers seat) just before the second.
but there is also a temp-probe in the up-pipe which detects if the pre-CAT is over-heating

[Perkul8r]

Ok. maybe I should have said this, and i am sorry, The car is not a factory turbo charged vehicle. Its a 1998 legacy with the NA 2.2, and i have assembled a turbo kit using stock parts. So the car itself has a factory exhaust manifold which will be fitted with a custom uppipe, and i am using the wrx downpipe. Thats why i was curious on 02 sensor placement. Sorry about that.

[Robbks]

ahhh, (i have a workshop manual for a USDM legacy 2.2)
what ECU will you be using? factory Leggy or splicing in a WRX ECU loom. (best option)

[Perkul8r]

Actually gonna use the stock 2.2 NA ecu. Looking into getting a Greddy Emanage, or a complete AEM EMS. But i have done alot of looking into this and i can run the turbo, with like 5 lbs of boost, and using a RRFPR and be ok. That is why i bought the wideband so i can watch my AFR's. But anymore than that and i will be pushing it. I am just looking to get the car going again. I was thinking about doing a SAFC for right now, but the Emanage is about the same price, and i believe you have more options.

[Robbks]

SAFC isnt worth the plastic it's housed in
and the e-manage is very limited.
fuelling changes of +/- 20% at only 5 RPM points.. not very good

take a look at the Haltech Interceptor (i have this on my GT Legacy and it works well) if you're after a piggy-back solution.
can be used to modify the existing mapping and also drive an extra injector too.
will do closed loop boost control, good data-logging to PC, etc

or also Haltech's Platinum Sprint500 can be used to control independent fuel and ignition maps in parallel with the stock ECU (16x16 mapping and user definable outputs and inputs)

but back on topic.
i would simply tap in the bungs in near enough to the factory locations so that you don't need to extend wiring looms etc.
if you're not running cats then it won;t matter, none of the readings will differ too much

also i suggest just using s set of stock WRX headers and up-pipe.
they'll all both to your heads i believe (correct me if i'm wrong)

[Perkul8r]

Sadly, The motor i have in the car has single port exhaust on the heads. So the Wrx stuff wont bolt up. When i am done rebuilding my other motor i will swap in the turbo cross member, and use the Wrx up pipe and exhaust mani. But thanks for the info on the Piggy back units. I really appreciate it.

[Sarra]

As a general rule, Widebands should be placed in the exhaust where they won't get too hot. Further down the DP is a good idea for the wideband.

Narrowbands, on the other hand, can be placed anywhere, but the closer to the engine, the better. Some Toyota and Honda cars actually have the front O2 in the manifold just inches away from the exhaust valves. You can cook a Narrowband, but it's hard. :p

[Robbks]

My Legacy TT has it's only narrowband in the exhaust manifold right at cyl2's exhaust port