O2 Sensor with 3-wires not 4-wires

Okay, Got a 87' 4.0, auto. Its been running very rich lately and I'm going to replace the O2 sensor on the exhaust down pipe. It is 3-wires! I thought all XJ O2 sensors were 4-wire. I got a print out of the FSM for an 88' and it says 4-wires. The colors, I think, are green, yellow and black. Just wondering if anybody would volunteer some more info on the 3-wire setup. Thanks...

Oh, I forgot to ask. Were is the cheapest place to purchase new O2 sensors?

I don't know what FSM you are using but the RENIX systems (what you have) use 3 wire O2s.

As an '87 your jeep is technically an AMC, and a haynes manual can be too generic when it comes to wiring diagrams

cheap O2? don't go there you will be buying another soon. Get a quality one and dont worry about it again.

Not saying your O2 isn't failing but a rich condition in a RENIX system is usually caused by the MAP sensor or a hole in the vacuum line leading to it.... you should look at that too.

since we are on the topic what kind is a good o2 sensor ? Item number ? Approximate price ?

pete

jeep dealer probably isnt going to have one for that year, otherwise i'd say get an OEM one.

Bosch, Standard, NAPA's Echlin line, A/C delco....not sure what brand Autozone carries but they usually have several options, just don't go the cheapest.

A 3 wire O2 should be around the 80.00 dollar range.

RENIX (and a great deal of other) O2/HEGO sensors are 3-wire - a two-pole heater, and a self-grounding signal. O2 sensors can have anywhere from 2-5 wires, and there are also (early) 1-wire O2 sensors (these are not heated.)

For brands, I usually use AC/Delco or Borg/Warner, and I've not had trouble with either. You should be able to find one, the other, or both locally for $50-60 with a little digging.

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