Cat by-pass install question...
 

I just passed my VA emissions inspection, which is valid for 2 yrs. Of course, that means I need a cat-by-pass pipe now. I recently had my exhaust all apart, so the bolts and gaskets are very new. I can handle the R&R, except I don't know how to get the O2 sensor off. My new pipe will have an O2 port. Before I get all excited, planning to have this done in an hour and end up stumped by the O2 sensor, I figured I'll plan it all out. Please help. Thanks.

Sorry Richard, but I don't really understand the problem.
The O2 sensor un-screws just like a sparkplug. You can cut the wire a couple of inches above the sensor, slip a deep socket over it, and screw it out. Use a butt splice and a bit of heat shrink tubing to re-terminate it afterwards.

That's the "good" news.......

The bad news is, if the sensor has been in there for a long time, it may be a bear to remove. On my car, it actually came out with the threads totally stripped. You may need a new sensor. Use Never-Seeze on the threads of the new one.

You'll like the small, but noticible power increase the cat pipe will give you. And like most cats, your Cat will enjoy the rest you're giving it.

Richard,
When I did my pipe I could not get my O2 off,I tried heat,blaster spray this thing would not come off. I think there is a special tool but I did not have it. I went to the local auto parts and bought a new 02 for $40.00
Good luck.

My O2 sensor came out really easy. Before cuttting any wires I decided to try a wrench on it... just a push and a tug and it started moving:D

As for the cat bypass... I don't know what muffler you're running, but the bypass adds a little bit of growl to the stock setup (no noticeable power). When used with a GHL dual out, the bypass is really loud.
Other than switching to SSI, most of the "noted" power increases were found using a Euro pre-muffler and/or a sport exhaust.
In addition to better power, the EPM is also quieter than the bypass.
I switched to a Euro-pre muffler and now enjoy good exhaust notes that no longer set off car alarms.

Any o2 will do at pep boys..it will just have a different connector. You want the 3 wire kind, tell them that, a hot line, sensor line and a ground

Thanks. That's a huge help. I thought new O2 sensors were ridiculously expensive. $40 is no problem. I can't wait!

There is a special socket designed to remove the O2 sensor without cutting any wires. It looks like a spark plug socket with one side removed. I would rather get one of those than cut the wires. FWIW my car felt like it had LESS power with the cat test pipe... I also have a B&B exhaust and was told that I did not have enough backpressure. At the highest RPMs it might have had a little more, but I don't always drive that way. It did make the car sound mean (much, much louder)- but the wife hated it. I put my cat back on and the car really did feel better.

BTW, what size is the socket needed, assuming I can find one with a slot in it?

I need to check, but I think they are all the same size- you just need to get an O2 sensor socket.

I think a 7/8 in. box end wrench will work on the O2 sensor. That's how I got mine off (no special socket). Not sure about the 7/8 in. size, but I know a SAE wrench worked. Just make sure it's a snug fit. Old O2 sensor is not gonna want to come free too easy!

As far as the backpressure thing goes..............

I put a set of B&B headers and muffler on my car. Also added a new EPROM. I won't say it's blisteringly fast, but it's definitely not slower!!! Definitely some more low-end grunt. Kinda loud too.

At the Funfest this weekend, I talked to a Bosch rep about the O2 sensor. He said "Do not cut the wire....get a special socket made for this at any auto parts store ....apprx $5". He says (and I don't know how I could believe this) that the wire also picks up some signal as well as the sensor.... so don't mess w/ it. This sound funny to me, but you should prob not cut it....He also said the sensor needs to be replaced every 60,000 miles or so. FYI

Since I have a 78, I have no idea about the O2 sensors. But if you are going to have to R&R the thing every two years, why not just buy a new one for the by-pass pipe and keep the one you alread have on the cat. Isn't it just a plug and unplug deal? It would make the R&R every two years a little less time consuming.

Well, ok, don't *you* cut the wire.
I *did* cut the wire, and after carefully splicing it back together, the O2 sensor continues to work just fine.
I guess I was too cheap/lazy to buy the *special" socket.
(Don't pay any attention to me. I'm just a wire cuttin' fool!)