TBI 3-wire O2 sensor upgrade, no open loop

[89S10_Project]

Good thread, I was able to xref that part number to OEM applications and now I can get a heated O2 sensor much less expensively, to use on my driver's side manifold for tu ning... another box to check on the project!

[lionelhutz]

You can only use that narrowband O2 for closed loop tuning. If you already have an O2 sensor for feedback into the PCM then it's rather pointless to add another one for tuning.

Overall, I'm not a fan of 3-wire sensors for any use. The 4-wire sensors are a similar price and that way you're not relying on the exhaust and engine block to be the ground for the sensor.

[89S10_Project]

I already have a 1-wire O2, in the downpipe where they all come together, stock location for the 4.3L V6 I sourced the y-pipe from (had to mod it to fit the V8).

I also have an available port at the driver's side head which is presently blocked with the old, broken O2 I took out of the above port.

I don't see any reason not to use that port for a (ok, 4-wire, like your point about the ground) O2 specifically for tuning. Folks on this board who know much more about tuning than I have suggested this approach.

[steveo]

I already have a 1-wire O2, in the downpipe where they all come together, stock location for the 4.3L V6 I sourced the y-pipe from (had to mod it to fit the V8).

I also have an available port at the driver's side head which is presently blocked with the old, broken O2 I took out of the above port.

I don't see any reason not to use that port for a (ok, 4-wire, like your point about the ground) O2 specifically for tuning. Folks on this board who know much more about tuning than I have suggested this approach.

a narrowband that isn't part of the closed loop trim system is practically useless...

[lionelhutz]

I believe you are mistaking a narrowband O2 sensor for a wideband O2 sensor. You use a separate wideband O2 sensor for tuning.

[Xnke]

Basically, 1 wire O2 sensors have to be within so many inches of the head-they're great for stock manifolds and the like because they rely on the exhaust gas to heat them up and keep them at temperature. Once you go to a long-tube tubular header, the exhaust gas temperature drops too much to reliably heat the sensor-so you go to a 3-wire or 4 wire sensor, incorporating a heater element to keep the sensor hot enough to function.

Outside of the added heater, and the separate signal ground for the 4-wire, there is zero difference between a 1 wire, 3 wire, and 4 wire narrowband O2 sensor. they function identically to each other, and are useless for open loop tuning.