[tchnprgrmr]

its really simple:

taken from probetalk

Single wire O2 sensor conversion originally conceived by ryanpzz, original pics by waderpgt modified by Omaha95PGT.

The single wire O2 conversion requires that you hack the old O2 sensor wires (it's a 4 wire). Do not hack the car's wiring harness. Just cut the wires at the base of the O2 sensor so you have 4 pigtails to work with. The old O2 sensor's 4 wire harness will still be plugged in but you just have to use 1 wire out of the 4. The other 3 should be insulated such that they do not contact anything (grounds, etc.). waderpgt recommended silicone tape, but paint on insulator or heat shrink tubing can also be used. Be sure to reuse the insulator sleeve that was originally on the old O2 sensor.

Some pics:

Bosch 11027 on the right and an old O2 sensor on the left
Bosch 11027 on the left and an old cut O2 sensor harness on the right

To review, you will be using the “universal” O2 sensor (no harness) version of the 1984 Chevy Caprice with the 3.8L V6 engine. The Bosch equivalent is the Bosch 11027 O2 sensor. Although there is a crimp connector on the universal O2 sensor, I’d recommend crimping then soldering the wires together in order to ensure a good contact.

The only difference between the single wire O2 sensor and the 4 wire O2 sensor is the loss of the ground wire (usually gray), and the 2 heater wires (usually white). The black wire is the sense wire. Functionally, the single wire O2 sensor should work exactly like a 4 wire O2 sensor except that the O2 sensor heater is gone which means that the O2 sensor will take a little bit longer to reach operating temperature. So instead of 30 seconds, it might take 2 minutes (n.b. arbitrary numbers) which means that the car will be running a bit rich a little longer until the O2 sensors heat up. If I understand correctly, the change to the 4 wire O2 sensor was done to reduce start up emissions.

Also, this conversion pertains to OBD-I cars (’93-’95 V6 KL engines). OBD-II cars look for the O2 sensor heater circuits to be intact. Since the conversion has none, it will return a CEL. You may have an option of splicing in a universal 3-wire O2 sensor which is a bit more expensive but still cheaper than a dedicated OEM type O2 sensor

To do a 3 wire conversion, hook up the 2 white wires to the heater circuit on the new universal O2 sensor. IMO, I would not do a 1 wire conversion b/c of the lack of the heater circuit. A 4 wire universal would be the best since it provides the O2 sensor with a dedicated ground and it would return a more consistent voltage. IMO, I think a 3 wire conversion would be serviceable and not pose any problems.