Engine O2 Sensor Question

Discussion in 'Fox 5.0 Mustang Tech' started by Husky44, Mar 29, 2014.


  1. Husky44

    Husky44 Active Member

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    Replacing the O2 sensors (car is 67 Mustang, engine is 91 5.0, no smog, stock computer, harness, etc, long tube headers). Not going to be doing any tuning immediately (donor car was tuned to match the TF HCI kit and stroker kit), but don't want to be replacing parts again if I want to tune later.

    Almost completely ignorant on tuning EFI; I've read on here enough to know that "wideband O2 sensors" or something to that effect is necessary for proper tuning.

    What do I need to buy now so that I have the capability to upgrade later, without buying replacement stuff?

    Thanks!
    Last edited: Mar 29, 2014
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  2. 7991LXnSHO

    7991LXnSHO Active Member

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    You need, if you really want to tune a carb or efi within the entire range of driving conditions, a weld on threadded bung, the wide band O2 sensor (2 for dual exhaust and both sides of a V motor), and the gauge or gauges with built in driver for the sensor. Digital outputs on the gauge would be nice too.

    That said, unless the changes are pretty radical, I doubt another tuning is needed with each part.
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  3. Husky44

    Husky44 Active Member

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    So if I'm replacing o2 sensors can I just order the "wide band o2 sensors" now, and add the gauges/ data management stuff later? Will "wide band sensors" operate in lieu of the stock o2 sensors, or do I need both? Will wide band sensors hook up to the stock sensors harness locations?
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  4. 7991LXnSHO

    7991LXnSHO Active Member

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    The 91 computer is meant for the stock sensors. If you keep it, (and unless you get really serious about computers, I would), the wide band sensors are going to be a second set, used for you to program a plug in chip, the fuel pressure etc.

    Now I did just read about a system that uses a new Mustang's computer, optional new harness, and the wide band sensors that sounded awesome and more than I needed to spend.
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  5. RacEoHolic330

    RacEoHolic330 I like to dress like a pretty girl SN Certified Technician

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    A wideband O2 sensor is completely independent from the stock O2 sensors. If you're not doing any tuning right now, just buy replacement narrowband sensors and go on your way. When you are ready to see what your air/fuel ratio is doing, pick up a wideband. There are lots of brands. A search on here will turn up people's favorites. As mentioned, you'll need to weld a bung near one of your stock O2 sensors. I will admit, when I first got a wideband, I didn't feel like welding a bung on my x pipe so I drilled a hole and JB welded the bung on. Held fine for years. The wideband will just need power and ground and you'll have to find a spot for the gauge.
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  6. 7991LXnSHO

    7991LXnSHO Active Member

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    Thanks, that is what I was trying to say, except for the JB weld. I have never used it in that high of a temp situation. Anyway, you can not just plug in widebands in place of regular O2 sensors.
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  7. Husky44

    Husky44 Active Member

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    Thanks for the clarification!

    I missed the whole Fox body era, so I didn't get to play with these like I did the first gen cars, and now the modern ones. I'm having to learn Fox -era tuning on the fly while building my 67. You guys are a huge help!

    Stangnet FTW!
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  8. Blown88GT

    Blown88GT Founding Member

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