extend O2 sensor wire... how to? [Archive] (2024)

macarollo

20th June 2010, 00:51

I want to buy an OBX header for my 99 miata. I think I will need a longer O2 sensor wire.

How can I do this? Can I just splice in 2 feet of extra wire? Anything special to consider? What is the best way to connect the wires?

JPT

20th June 2010, 01:15

You can buy the Racing Beat extension set:
http://www.racingbeat.com/FRmiata.htm

Or you can just splice wire. Just solder and heat shrink with similar gauge wire. Would strongly recommend that you add plastic loom or sheathing to protect it. I went as far as wrapping the loom in electrical tape to look OEM.

When you decide how much you want to lengthen it, double-check under the car first and plan how you intend to mount the wire. Mine was a little longer than anticipated, and sat on the midpipe and started melting the wire sheath. Tightened a lot of slack and it's ziptied behind the engine, but if you could get the length just right, it'll be a nice, clean install. Also take into account how you will mount it midway through the transmission tunnel, so securely mounted.

Jerry & Cootie

20th June 2010, 05:17

The instruction phamplet that comes with the Bosch O2 universal says DO NOT solder the leads. :confused:

I used the clamp fitting that came with it.

lynskey

20th June 2010, 06:49

macarollo

20th June 2010, 09:29

Here is what I did on an OBX Header and it works great.
http://cpwstore.carpartswholesale.com/catalog/details/Mazda/Miata/Denso/Oxygen_Sensor/1999/NP2344209.html
Remove your old 02 and cut the wires as close to the sensor as possible. This new Universal 02 comes with 11 inches of lead wire. Most have 15cm [5 inches]. Go inside the cool house and use the diagram provided to match to your O2 sensor wires. Buy a pack of wire shrink tube at wally world and after you have triple checked your wiring. Use the provided clamps and using the heat shrink tube. Heat the tubing and wrap it with electrical tape. Once your header is on the car. Screw in the 02 and put the leads back in the factory position in the clamps. You can find some cheaper than the one I gave the link to. A 20cm [7.9 inches] lead will work also. Good luck.

Why would I want to buy a new O2 sensor (mine works fine) if I could just buy some regular wire (to extend my current one) of the same gauge?

socal pat

20th June 2010, 09:45

macarollo

20th June 2010, 22:51

randy f

21st June 2010, 00:52

so is it safe to crimp a wire in and shrink wrap it? Has anyone else done this?

Yes and YES

Chuck75

21st June 2010, 04:32

The O2 sensors do not use "regular copper wire" A splice from the O2 wire to copper wire can introduce a voltage offset in the output. How much ? I'd need to look up thermocouples and data in references that I haven't used or had for almost forty years.

Is the offset really a problem? I doubt that it is on a narrow band sensor.
I'd think that possible corrosion/oxidation and a resulting poor connection is a significant concern. The narrow band sensor usually has a full output of one VDC, and at the optimum mixture, averages about half that as it swings from one volt to a lesser value.
Remember that two splices can double the offset.

Bosch O2 splicers are convenient. You may even find the correct wire on the internet.

Jerry & Cootie

21st June 2010, 06:33

macarollo

21st June 2010, 08:46

Sam

21st June 2010, 09:33

haven't seen a stainless steel wire on an O2 sensor yet, nor heard of one; the shiny silvery color is solder tinning (yes, even the Bosch; I have one), all the wires I've seen or heard of have been copper, or the author was guessing. So, there shouldn't be a significant potential at the joint.

Somehow that stainless steel thing has become one of those internet fictions. You'll know if you've got stainless steel because;

a. it's quite a bit stiffer for its diameter than copper, and
b. it won't solder with ordinary lead-tin solder and normal temperatures.

I'm still waiting to see actual stainless wire on one of these. No reason for it, for one thing.

as for crimping; the much-vaunted Bosch connectors do essentially that, only they're also take-apart and very clever, use 'em if you got 'em. Way too much worry for what is a simple task. Just keep it away from things that are hot, make sure it's actually insulated, and it'll work fine. This is not rocket surgery.

JWR-MX5

21st June 2010, 11:50

haven't seen a stainless steel wire on an O2 sensor yet, nor heard of one; the shiny silvery color is solder tinning (yes, even the Bosch; I have one), all the wires I've seen or heard of have been copper, or the author was guessing. So, there shouldn't be a significant potential at the joint.

Somehow that stainless steel thing has become one of those internet fictions. You'll know if you've got stainless steel because;

a. it's quite a bit stiffer for its diameter than copper, and
b. it won't solder with ordinary lead-tin solder and normal temperatures.

I'm still waiting to see actual stainless wire on one of these. No reason for it, for one thing.

as for crimping; the much-vaunted Bosch connectors do essentially that, only they're also take-apart and very clever, use 'em if you got 'em. Way too much worry for what is a simple task. Just keep it away from things that are hot, make sure it's actually insulated, and it'll work fine. This is not rocket surgery.

Actually, even if the sensor wires were of a different material to generate a offset voltage that voltage would cancel itself out because the wire junctions would go +something>copper -something>copper, for a net voltage gain of -0-.
All of the universal sensor wires that I have seen are tinned copper and a proper compression splice with a bit of heat shrink that has the inside melting layer should make a satisfactory connection. Just be sure to protect the outside by running it inside some heat-resistant sleeving for anything that might be near an exhaust pipe.