Oxygen sensor question

[Fourth Horseman]

I need to tap the collective wisdom here at mm.net: I'm putting am A/F ratio gauge in my car. I need to tap into an OS2 sensor to do it. From searching the forum I know which wire I need to tap, but which sensor should I go after? The one right after the exhaust manifold, or the one between the two cats? Or perhaps does it not matter?

[torinodan]

After the manifold, it's the truest reading from your engine.

[Fourth Horseman]

After the manifold, it's the truest reading from your engine.

Thank you, sir! :bows:

[BillyGman]

After the manifold, it's the truest reading from your engine.Absolutely!! BEFORE the cats. NOT after. :nono:

[SergntMac]

I suggest you select the driver's side, first sensor, closest to the exhaust manifold towards the front of the car. This is near where an add-on bung should be installed for correct dyno tuning.

The passenger side fuel rail gets fuel first, and the driver's side fuel rail is the end of the line. If you are running lean, or, rich at the end, the fuel system before that is getting more fuel. In other words, seek out the worst case scenario, address it, and the rest will fall into place.

You should consider having a separate bung installed, and purchase a wide-band sensor, such as Bosch, or, a DynoJet AFR kit to monitor your AFR from the cabin. It is more accurate, and will come in handy when (if) you dyno tune.

http://www.widebandcommander.com/

Happy Motoring!

[BillyGman]

Speaking of O2 sensors.....does anyone know how long they're supposed to last? And is there any Ford recommendation for replacement as far as amount of mileage?

[fastblackmerc]

Speaking of O2 sensors.....does anyone know how long they're supposed to last? And is there any Ford recommendation for replacement as far as amount of mileage?
They should last as long as the emissions warranty, 50,000 miles I think. I don't believe there is any recommended change interval. Replace it when it goes bad, usually when you get a "check engine" light and the code calls out the sensor.

[David Morton]

Last I heard, the emissions warranty was 100,000 miles.

Lead in the gas will make them go bad.

[BillyGman]

Okay. Thanks for your replies on that. :up:

[CRUZTAKER]

50k was my understanding .... but I could be wrong.

I added a separate stand-alone bung...no wire tapping.