Ladybug83

I believe the core of the green wire was stranded as well.

dr bob

I'm guessing that the shielding was included to help protect the relatively high impedance sensor signal from inductive noise 'shared' by all the cabling at the bottom of the CE panel. While it might be ideal to have a continuous shield with grounding at both ends, there's no available ground point at that end. One would nee to fabricate a small bracket, perhaps using a bulkhead BNC or similar small-coax fitting through the bracket.

Looking at the later cars with heated sensors, the wiring for the heater (power supplied by the fuel pump relay) has all three conductors unshielded and untwisted. Whatever noise protection was imagined, it was not a problem in the later cars.


And a FWIW on soldering the sensor cable -- I solder spliced the sensor and heater wires a few times now with sensor replacement, and it's working fine. The sensor wire itself is small, and has thin kynar or similar insulation on the stranded conductor. Hard to believe that the sensor actually expects to see a reference oxygen sample drawn through that wire and insulation. There is nothing to cause such a flow that I can see, even if the wire were snaked through a straw with an air gap around it. My casual experience.

hernanca

All years with O2 sensors show shielding on the signal wire in the wiring diagrams I am looking at (gray workshop manual and pdf’s):

80-94 show a shielded O2 signal wire (with 83-94 showing the heated sensors). That shielding is always only shown on the signal wire and always only for that part of the signal wire going from the connector (inside the car) to the computer. However, the part of the signal wire coming in from the O2 sensor (outside of the car), coming in through the grommet in the floor/tunnel, and ending at the connector (inside of the car) is never shown shielded.

I don’t have an electronics background, so I may not be clear in my description. Below is a wiring diagram for the 1994 MY. The green marking follows the shielded wire to pin 24 on the computer with pin 5 (shown beside it) being used to ground the shielding.