TBI 3-wire O2 sensor question

I'm in the process of replacing my stock one-wire o2 sensor with a this heated unit, per Dave W's recommendation. It's installed and wired in, but I haven't run it yet. (In the process of also replacing some oil cooler lines). Should the unit get hot around the base? I've got it wired so it gets 12v with ignition on, but I'm not feeling any heat around the base of the sensor or the exhaust pipe. I tested it by leaving ignition on for a couple minutes, but I didn't notice any temp change at all just by touch. I did test voltage and ground at the sensor connector - everything seems good. Normal behavior or is there a problem?

Yes you should feel the o2 sensor warm up by touching the base of it we're it goes in to the exhaust.

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Originally Posted by Stroked 388

Yes you should feel the o2 sensor warm up by touching the base of it we're it goes in to the exhaust.

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Great, thanks. I'll check my wiring again and if still nothing I'll take it out and bench test it with 12v.

Check that you have the 2 wires the same color wired as the heater or to power and ground. The 3rd wire that is another color is the sensor output. I'm talking wires from the actual sensor here, not the pigtail the sensor plugs into.

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Originally Posted by lionelhutz

Check that you have the 2 wires the same color wired as the heater or to power and ground. The 3rd wire that is another color is the sensor output. I'm talking wires from the actual sensor here, not the pigtail the sensor plugs into.

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Will do, thanks. That is how I remember wiring it - I bought a 3-wire harness from Dave W so it was pretty idiot-proof -- but I'm not home to check it right now.

Anyone have a part number for that 3 wire O2 sensor? Looking to change mine to heated.

Edit: never mind I saw the Op had a link.

Mine is 4 wire 2 hots 1 signial and a ground is that the one your referring to ?

ACDelco ASF-74 is a factory 3 wire O2 sensor for a 1994 S10 4.3 Liter.

https://www.ebay.com/itm/ACDelco-AFS...UyV:rk:13:pf:0

dave w

I checked my wiring again tonight and yep, no issues. So I took the sensor out and hooked it up to 12v - after about 3 minutes the tip got pretty hot. I could still very briefly touch it without getting burned. Should it get hotter and should it warm up faster, or is this expected behavior?

that is about how mine worked, before I put the 3 wire in truck would go open loop at 30 mph in 5th gear in the winter time.

Thanks for the input. I think I'll put it back in and run with it and see how it goes.