WRX exhaust question

[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?

[impreza_GC8]

You need to buy/acquire/steal/build an extension harness for the sensor.

[lucas]

would an extension harness just constitute elongating the wires?

[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.

[lucas]

the stock wrx spot is right past the DP in the cat pipe. Will that work?

[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.

[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.

[ericem]

Problem is, if the o2 sensor sees its to lean, it will keep richening up the mixture.

[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?

[SLODRIVE]

You want it BEFORE the cat.

[lucas]

before the cat roger roger. why though, just so i know?

[ericem]

lol, SO THE o2 sensor gets a proper reading. AFTER the CAT it would be reading leaner haha.

[lucas]

thats what i figured, just making sure

[RJ93SS]

btw, the wrx exhaust hangers wont lie up and the exhaust is to short

[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.

[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

[ericem]

lol good to know thanks.

[lucas]

getting my stupid car to pass smog is getting harder every day. damn

[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?

[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.

[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?