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WRX exhaust question

Posted: Tue Jan 05, 2010 6:15 pm
by lucas
my poor leggy wont pass smog so ive acquired full wrx exhaust with all the cats and stuff. the question i have is the o2 sensor is in a different location on the wrx setup, where as the o2 on the leggy is in the down pipe. anyone have experience with this problem or have heard of what to do?

Posted: Tue Jan 05, 2010 6:29 pm
by impreza_GC8
You need to buy/acquire/steal/build an extension harness for the sensor.

Posted: Tue Jan 05, 2010 7:04 pm
by lucas
would an extension harness just constitute elongating the wires?

Posted: Tue Jan 05, 2010 7:20 pm
by ericem
You need to add a bung BEFORE the cat, if you put the o2 after the cat it will always think the engine is lean.

Posted: Tue Jan 05, 2010 7:23 pm
by lucas
the stock wrx spot is right past the DP in the cat pipe. Will that work?

Posted: Tue Jan 05, 2010 7:37 pm
by SLODRIVE
That's the rear O2 bung. The WRX/STi primary O2 sensor is in the exhaust manifold...it might be easiest to have a bung welded to the downpipe, upstream of the cat.

Posted: Tue Jan 05, 2010 10:34 pm
by lucas
even if the car runs lean for the test that should be better right? i mean it will only be on there for a day.

Posted: Wed Jan 06, 2010 1:26 am
by ericem
Problem is, if the o2 sensor sees its to lean, it will keep richening up the mixture.

Posted: Wed Jan 06, 2010 6:27 am
by lucas
yeah i thought about that after i thought it would be ok. well looks like i need to get a fitting put on the WRX down pipe, should i put the fitting before or after the CAT, im assuming after right?

Posted: Wed Jan 06, 2010 6:30 am
by SLODRIVE
You want it BEFORE the cat. ;)

Posted: Wed Jan 06, 2010 6:32 am
by lucas
before the cat roger roger. why though, just so i know?

Posted: Wed Jan 06, 2010 4:47 pm
by ericem
lol, SO THE o2 sensor gets a proper reading. AFTER the CAT it would be reading leaner haha.

Posted: Wed Jan 06, 2010 6:21 pm
by lucas
thats what i figured, just making sure

Posted: Wed Jan 06, 2010 6:26 pm
by RJ93SS
btw, the wrx exhaust hangers wont lie up and the exhaust is to short

Posted: Wed Jan 06, 2010 8:01 pm
by ericem
Have you tried? The mid, and exhaust hangers appear to look like they will all hook up and are in the same location. Just not 100% if I need to extend part of my mid pipe to meet my wrx 3" bell dp.

Posted: Wed Jan 06, 2010 8:44 pm
by RJ93SS
yes, with a custom built titanium wrx exhaust.. you may have some luck with the first hanger, but definitely not the muffler hangers. the hangers on my exhaust pipes are adjustable so i made it work. i also had to add a 7" extension.

but things change with a dp. i had to hack my midpipe to bend the exhaust and reweld it to change the angle as it was hitting the diff.

but, there's a few write ups about it and ways to make it fit. it is not a direct bolt on though

Posted: Wed Jan 06, 2010 10:00 pm
by ericem
lol good to know thanks.

Posted: Thu Jan 07, 2010 7:37 pm
by lucas
getting my stupid car to pass smog is getting harder every day. damn

Posted: Fri Jan 08, 2010 8:36 am
by lucas
does anyone have a picture or a link i can look at to see what i need to do to get the wrx exhaust to fit?

Posted: Fri Jan 08, 2010 6:30 pm
by ericem
If appears it will only require you to use the stock muffler. I compared my wrx to stock. And the muffler is different (the mounts and pipe length). But the wrx dp, and mid pipe should be fine matted with stock muffler.

Posted: Fri Jan 08, 2010 7:00 pm
by lucas
yeah thats the problem i dont have any of the stock pieces left. does an n/a muffler have the same length as the turbo one?