Putting O2 sensors into rear cats on MY03>

[atmorris]

I'm installing headers on my '03 and the main cats do not have any capped bungs for relocating the post cat O2 sensor to. The parts diagrams show them located in the angled end face of the cat on the stock main cats that have them. Can anyone tell me:

1) Where can I get weld on receivers(fittings) for the O2 sensors? Pellican lists a weld on receiver PN PEL-SW85-21688 for a K&N Air/Fuel Monitor. Does anyone know if this fitting would work?

2) Should the fittings be installed into the angled end face of the cat or onto the pipe exiting the cat ? Would one location be preferrable over the other?

3) Failing all else, does anyone know what the size/tpi size of the stock O2 sensor is ? I could always just weld a nut on there.......

Andy

[z281974]

Andy,

(1) You can pick up Oxygen Sensor fittings online at www.summitracing.com. The part number is SUM-2990 at $5.95 for the standard one, and SUM-2990S at $6.95 for the stainless one.

(2) I would recommend locating the fitting on the pipe after the cat. You can look at some of the sport cat's that contain these fittings to gain an idea about location.

(3) You can then cut and solder in some additional wire length to the Oxygen sensor leads as required, using heat shrink to seal. I believe that the longer leaded second O2 sensor assembly will fit the new configuration's closer location, and only one set of leads will need to be lengthened.

I haven't done this yet, as I'm still concerned about possible CEL's, but I've heard of this approach working several times when using headers with sport cats. Using the original cats with an added O2 sensor should be equivalent. Good luck.

Tom T.

[atmorris]

Andy,

(1) You can pick up Oxygen Sensor fittings online at www.summitracing.com. The part number is SUM-2990 at $5.95 for the standard one, and SUM-2990S at $6.95 for the stainless one.

(2) I would recommend locating the fitting on the pipe after the cat. You can look at some of the sport cat's that contain these fittings to gain an idea about location.

(3) You can then cut and solder in some additional wire length to the Oxygen sensor leads as required, using heat shrink to seal. I believe that the longer leaded second O2 sensor assembly will fit the new configuration's closer location, and only one set of leads will need to be lengthened.

I haven't done this yet, as I'm still concerned about possible CEL's, but I've heard of this approach working several times when using headers with sport cats. Using the original cats with an added O2 sensor should be equivalent. Good luck.

Tom T.

Thanks. I just ordered them. Apparently they are all 18mm as I thought. I'm a little concerned about CELs too, but I figure I'm never gonna know until I try so......

Quite a few people have told me that they have lengthened their wiring harnesses on the O2 sensors without trouble. The key simple seems to be to do a good job when you do it, and don't solder the connections. Even Bosch's universal O2 sensor installation kit instructions refer to crimp connections.

[z281974]

Thanks. I just ordered them. Apparently they are all 18mm as I thought. I'm a little concerned about CELs too, but I figure I'm never gonna know until I try so......

Quite a few people have told me that they have lengthened their wiring harnesses on the O2 sensors without trouble. The key simple seems to be to do a good job when you do it, and don't solder the connections. Even Bosch's universal O2 sensor installation kit instructions refer to crimp connections.

Glad you were able to quickly order them. I used one of them a few years ago on another car. As far as soldering goes, there's no electrical / electronic reason not to solder an O2 connection other than potential corrosion, where a good heat shrink cover has proven effective. Crimping is ok too, if you prefer that. Keep us informed on the project, as I'd like to duplicate your successful efforts on my 01S. Thanks.

Tom T.

[atmorris]

The solder/crimp thing may be based on the difficulty of acheiving a good solder joint between unlike materials. The factory harness uses stranded SS wire. Most people are going to use stranded copper for the extension.

One guy on this board had told me he tried both methods, doing one extension with crimps, and soldering the other. He said that he got a CEL on the soldered extension after a short time, but never did on the crimped extension. He revamped the soldered extension using crimps and hasn't experienced a CEL since (2 years). Interesting.

[z281974]

I've never heard of stainless steel wire used for elctrical / electronic connections before. Automotive wire is usually either bare copper or pre-tinned copper (which may resemble stainless). But if the wire really is stainless, then you can't solder it. I based my soldering recommendation on my successful soldering of a Bosch O2 sensor on my Mercedes about 4 years ago, without subsequent CEL's. I can think of no reason why a properly soldered O2 connection would not work. I'm a retired engineer with 30+ years of the military / aerospace experience, so I'm not just talking off the top of my head. But on the other hand, a proper crimp will work too, and may require less expertise to implement. In any case, good luck with the project and keep us informed of your progress.

Tom

The solder/crimp thing may be based on the difficulty of acheiving a good solder joint between unlike materials. The factory harness uses stranded SS wire. Most people are going to use stranded copper for the extension.

One guy on this board had told me he tried both methods, doing one extension with crimps, and soldering the other. He said that he got a CEL on the soldered extension after a short time, but never did on the crimped extension. He revamped the soldered extension using crimps and hasn't experienced a CEL since (2 years). Interesting.

[atmorris]

Don't know on the SS issue, just going by what one person here who had done his told me. You may very well be right on that. I don't see why a solder wouldn't work either, again just going by what I have been told by others who have done it.

I'll let you know what I find.

P.S....Just because your a retired aerospace engineer, doesn't mean you were a GOOD one... :P

just kidding, of course.... :lol:

[atmorris]

I've never heard of stainless steel wire used for elctrical / electronic connections before. Automotive wire is usually either bare copper or pre-tinned copper (which may resemble stainless). But if the wire really is stainless, then you can't solder it. I based my soldering recommendation on my successful soldering of a Bosch O2 sensor on my Mercedes about 4 years ago, without subsequent CEL's. I can think of no reason why a properly soldered O2 connection would not work. I'm a retired engineer with 30+ years of the military / aerospace experience, so I'm not just talking off the top of my head. But on the other hand, a proper crimp will work too, and may require less expertise to implement. In any case, good luck with the project and keep us informed of your progress.

Tom

The solder/crimp thing may be based on the difficulty of acheiving a good solder joint between unlike materials. The factory harness uses stranded SS wire. Most people are going to use stranded copper for the extension.

One guy on this board had told me he tried both methods, doing one extension with crimps, and soldering the other. He said that he got a CEL on the soldered extension after a short time, but never did on the crimped extension. He revamped the soldered extension using crimps and hasn't experienced a CEL since (2 years). Interesting.

Just for information - I did the wiring harness extensions this weekend. The stock harnesses do, in fact, contain SS stranded conductor. It is not pre-tinned copper.

Also, we put the O2 sensor bungs in the pipe, not in the endface of the cat. When we drilled a pilot hole in the stock position (according to parts diagrams) on the endface of the cat, we ran into a second surface about 1/8" below the outside surface of the cat. We stopped right there, welded the hole closed, and put the sensors in the pipe instead.

Andy

Edited March 26, 2007 by Andy_M