legacycentral bbs

i want to remove both my cats. and have strait pipe all thee way back. what do i do about my o2 sensor? will this affect it any ????

You should probably weld an oxygen sensor bung onto the downpipe. A lot of people just weld on a spark plug non-fouler, which has the right threads for most oxygen sensors too.

The engine will run without the sensor but it's better to have the feedback loop present so it can learn better air/fuel mixtures and so it doesn't switch to an extra-conservative timing map.

sounds right to me thanks a lot on a fast response.

Heres an interesting angle on this topic. What if you remove the downpipe and rather than having the o2 sensor in the downpipe you have a wrx up pipe with the bung on it already. Could you have the o2 sensor before the turbo?

Mike

I don't see why not... The turbo really has no effect on the A/F ratio once it leaves the engine...

It would work okay unless the heat was too much for the sensor. A turbocharged engine's exhaust gas is usually much hotter than a naturally aspirated one before the turbo uses some of the heat, and some sensors can't handle those high temperatures.

Doesn't a WRX up-pipe have a catalytic converter in it?

Most WRX catless downpipes come with the bung for the O2 sensor. It is just farther down the pipe and you have to extend the wires on your sensor to reach.