CO sensor plug question
 

I attempted to unplug my oxygen sensor the other day and I cracked the male connector (this is the connector inside the engine compartment). Knowing that it was cracked, stupid me, I still tried to pull on the plug. In doing so, the wire was pulled from the housing connector. Easy fix?...it looked like it until I spliced the wires and found that it had a co-axle type of wire. My question is how do I hook or splice this connection back to my sensor? I talked to a shop and they mentioned this plug is part of the main harness. In other words, if I want the same connector, I will have to purchase the whole harness (bbbbbux)! Can someone help me determine if I can fix this without purchasing a complete wiring harness for my car? Would I need to ground one of the co-axle wires and then connect the center one to my sensor?

Thanks in advance.


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John
'81SC Targa

Why do you want to reconnect the sensor?
Just leave it off. The car will run cooler and more smoothly. You may want to adjust the mixture to compensate. If you want info about why/how this works...search the archives. It is replete with postings on this.

Nick.

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_ _ __ _ _
Nick Shumaker
1982 911SC Coupe
nickshu@yahoo.com
PCA -- Rocky Mtn. Region

it should work fine in spite of the broken housing. you would just want it to work for emission tests anyway.

Nick - I usually have it unplugged but I need it when I have my car smogged.

JW - The wire is separate from the housing. I can't use the housing anymore. All I have now is a piece of wire that is the co-axle type coming from the back of the firewall. My question was how could I re-connect it to my sensor? The wire from the sensor seems to be a single wire where as the one coming from the harness is that dual co-axle type wire.

Thanks for your responses.


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John
'81SC Targa

FYI - it is "co-axial" not co-axle. Correction "coaxial" (thanks Warren).

Charlie

[This message has been edited by cds72911 (edited 10-29-2001).]

Well, actually, it is 'coaxial!'

If you want to have an easy modification of the engine harness that can be readily disconnected safely and no danger of crumbling, why not install a pair of BNC connectors for a small-sized cable, such as RG-58/U, RG-174/U, or RG-180/U? Assuming that you have or can get a small soldering pencil of low-Wattage, it will only take five-ten minutes per connector. Sealing the plug that screws in the body of the connector with silicone glue/caulking would be a good idea for the best weather resistance.

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

Warren,

I'm a little confused here. I don't understand why the wire coming into the engine compartment to the connector is a 'coaxial' wire. If it's a coaxial, aren’t one ground and the other hot? Can't I just ground the outside wire and connect the center one directly to the OC sensor? Where can I purchase these BNC connectors? BTW, thanks for the correction for the 'coaxial' spelling.


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John
'81SC Targa

John,

Yes, if you can solder ... there are many kinds of connectors that could be attached.

But, BNC connectors were developed by the Navy (Bayonet Navy Connector) and are designed for coax cables, and are highly reliable in all kinds of harsh conditions. Any major electronic component supply house such as Allied or Avnet (not Radio Shack) will have them in stock for $4-$5 per connector.

The reason that cable is shielded coax is because the O2 sensor output is less than 1.0 Volt, and shielded cable prevents noise from the ignition system from causing problems.

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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler

Well this is being resurected from a long time ago, but I am having this problem. So I get the BNC connections, where do I cut? Do I take the big black thing, sorry I just dont know what it is called, out? Mine is loose at that point.

BTDT. Mine crumbled, i stuck it back in, eventually the wire got frayed and stopped making a good connection. Car ran like crap with hte lambda computer swinging the mixture slowly and too far each way. i cut and spliced in a new standard water resistant connector, bingo. car started running right again.
Here's a thread that details what we are talking about, including an excerpt form an article written by lee Rice (smart cookie) on the subject. http://forums.pelicanparts.com/porsche-911-technical-forum/182054-what-part-am-i-looking.html?highlight=sensor

Thanks for the link, so seeing how I have a 83 I need to find a male and female connection with 3 points?

If Mr. Rice's '78 SC had an oxygen sensor, it had an '80 or later engine transplanted into it because the '78s didn't have O2 sensors. However, that is a strange plug. I've not seen one like it elsewhere, and certainly not elsewhere in a 911. It looks like the wire from the plug forward in the wire loom to the little computer under the passenger seat (this is a separate loom from the main loom) is or may be coaxial. And it gets its ground, I think, from where it connects to the computer. I think that is all that is required for the outer braid to do its shielding job.

The SC oxygen sensor is a one wire sensor, and that one wire is all there is from the sensor to the plug in question. So the advice to just use some other kind of connector is good. A BNC connector is overkill, because the shielding stops at the connector.

Walt Fricke

If the car still runs right with the male plug just stuck back in the female plug, life is good for now. Don't mess with it until you are ready But eventually it will need to be addressed.

On mine, I installed a three wire O2 sensor instead of the single wire, so i have basically the same set up as you except for the type of connector and harness.
I found a spare two wire connector to supply the power to my sensor heater just sitting in my engine compartment that fit the upgraded O2 sensor perfectly and plugged it in, lord knows what it was supposed to be used for. Maybe rear wiper, who knows. It works. So all i had to do was replace the connector for the signal wire.

Bottom line is, if you can seperate the signal wire from the main connector then you only have to splice in a single connector. If you can't seperate the signal wire from the two power wires, you will have to replace the main connector with a 3 wire connector.

Should I use plastic or a metal clip? ANd where do I make the cut?

Bump