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Air/Fuel ratio gauge?

Discussion in 'The Garage' started by Jonny-K5, Sep 29, 2004.

  1. Jonny-K5

    Jonny-K5 1/2 ton status

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    thinking about getting one of these. aynone else run one? if so what brand? worth it? i think it would make tuning my carbed motor easier when i do mods. but all the kits i've seen are pretty vague. i'd like a digital gauge that accually told you 13.2,14.1 etc.

    what do ya think?
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Not sure if you realize it or not, but you'd need a wide band O2 for the tuning you describe. "Narrow band" O2's switch between rich/lan, and thats about all you will get out of one.

    Last I knew, the wideband O2's were pretty darn pricey.
     
  3. outlawtorn

    outlawtorn 1/2 ton status

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    not worth it lol, when the ****er runs it runs /forums/images/graemlins/deal.gif
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It runs from 5:1 to 20:1. That doesn't mean it's running correctly.

    I think it's a cool idea.
     
  5. Jonny-K5

    Jonny-K5 1/2 ton status

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    ya i've seen the ones with narrow band O2's. pretty lame. just a green light for lean and red for rich.

    does anyone know who makes a wide ban O2 gauge that is fairly accurate? the closest i've seen is one with a bar graph so at least you have eight lights instead of two. still not as precise as i'd like. i know they are pricey, but i want one that displays actual numbers
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I say spend some time over at thirdgen.org, or maybe someone has some other forums to suggest, where stuff like O2 tuning is discussed at length.

    Even a narrowband will at least tell you if you are running consistently lean or consistently rich (such as under hard acceleration) but for example, during part throttle cruise, O2 jumps from rich to lean a lot.

    I'd go out and see if you can find a file of the datastream from an 8192 baud connection to a GM ECM, to see if what you want is even worth it. I'm not saying it would or would not be worth it, just that again, O2 jumps a lot, and I'd be surprised if it was something that can be measured "cheaply" and accurately. There are certain electrical things that can't be measured with a digital multimeter because they happen too fast, and an analog(?) multimeter is used instead.

    O2 voltage output is very small, so I suspect it would have to be pretty darn sophisticated to turn that into something you could read, and realtime. Check it out! /forums/images/graemlins/smile.gif
     
  7. Jonny-K5

    Jonny-K5 1/2 ton status

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    hmm, food for thought /forums/images/graemlins/thinking.gif thanks
     
  8. Rolled

    Rolled 1/2 ton status

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  9. Blue85

    Blue85 Troll Premium Member

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    I have thought about adding one, too, but I'm not sure it would help that much with tuning. There are a lot of them on the market that claim to measure a few levels in each direction of stoich, but I'm not sure they are really intended to be anything more than a gadget.

    The wideband sensor would be great for tuning, but I think they were only made for one Honda and one supplier controls the whole supply, so the price remains really high. You could use a standard multimeter to do your tuning with one of those, though.

    I have also thought about building an engine controller that takes advantage of a wideband sensor when I finally go fuel injected. /forums/images/graemlins/thinking.gif
     
  10. sandy78

    sandy78 Registered Member

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    Yes, I have used one. Yes it works. I live in an area where I must emmission the vehicle every year to license it. I used the A/F ratio indicator to dial it in and have passed easily every year since I built my motor and set it up. I used the Summit LED bar gage and mounted it in the vacant pod in the lower left of my instrument cluster. I used the cheap 2 wire O2 sensor also from Summit, had the muffler shop weld in a bung in the pass. side collector, and off I went. Total cost approx. $65 in parts and $10 to the shop to weld in the bung. With every jet/rod change in the carb, I could see the results. I have never had to mess with anything after I set it up. Notes: Mount the O2 sensor as close to the motor as possible - tough with headers, or use the more expensive 4wire heated sensor. My gage was at the limit in the collector, and would sometimes drop out because the exhaust temp at the sensor would become too "cool". Also, I only monitored one bank. You could have a bung in each side and move it back and forth, or set up dual systems.....Lastly, my O2 sensor didn't hold up to deep mud/water (submersion). Overall, I found it way better than guessing or trying to read plugs.
     
  11. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    I've been reading this thread and thinking about doing this myself. My headers already have a bung and it is farther up than the collector.

    My thoughts/questions:
    Sandy78, did you just use it as a guide for setting idle mixture only?
    It would seem based on what I've read on this thread that idle is really the only reliable place to use it. Which makes sense to me.
    Or would it be useful at other times. I'm thinking maybe off idle acceleration. Wouldn't the reading then give indication of whether or not the jetting was correct?
    At the very least it's got to be at least as good as the vacuum or handheld tach methods.
     
  12. Scuba Steve

    Scuba Steve Registered Member

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  13. Jonny-K5

    Jonny-K5 1/2 ton status

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    that nordskog piece is pretty nice. i dont know how i missed that one, ive looked over jegs and summit.
    i wonder what type of O2 sensor is needed for this one. they didnt specify.
     
  14. Scuba Steve

    Scuba Steve Registered Member

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    Sorry messed up the link to the Nordskog page on the last one. This tells you what you need. You can also select what color face and bezel by changing the last 2 numbers of the gauge. 0 is for black, 1 for white, or 2 for silver face and the bezel is B, W, or S. ie: D70142S would be silver face with silver bezel. You just have to search for it by part number on summit.

    Nordskog gauge info clicky
     
  15. Blue85

    Blue85 Troll Premium Member

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    I suppose with a tach, an A/F gauge and a vacuum gauge in the cab, you could spot problems in any performance region. I'm skeptical about how it would do at WOT, since the ideal mixture might be in the full rich region of the gauge, but for part throttle and cruising, it should give useful information.

    Do they list any specs as to the true accuracy?
     
  16. Jonny-K5

    Jonny-K5 1/2 ton status

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    [ QUOTE ]
    I'm skeptical about how it would do at WOT, since the ideal mixture might be in the full rich region of the gauge, but for part throttle and cruising, it should give useful information.


    [/ QUOTE ]

    in theory you'd want the A/F ratio around 12.8 at WOT. so if its pegged out on the rich side its probly too rich. guess it all depends on what kind of engine combo you are running. i know some supercharged engines run around 10 to 1 as a means of preventing detonation.
     
  17. sandy78

    sandy78 Registered Member

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    Yes, you can see results of rod and or jet changes. I had forgotten, but when I was tuning, I used a vacuum gage temporarily mounted in the cab so I could also see if it was a spring tension issue. For example, I tried the different primary springs from a kit I got from Edelbrock, but ended up back at stock with maybe one coil clipped off. Also, if tuning a Quad, you can see how the secondaries come in as well as the final WOT A/F ratio. Lastly, with a carbed motor, tune slightly to the rich side of the gage. Right on center (stoich) ran a little weak. Sweet spot with my combo was one or two segments up from center. Bottom line is that I get a dyno smog test each year, and it runs 1/4-1/3 of the specified limits for a 350 and it is a mild 383. Keep in mind that I am running a quench setup on this engine which helps keep detonation at bay even as you get pretty lean.
     
  18. Smitty

    Smitty 1/2 ton status

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    Might try checking the Autometer air/fuel guage. It has about a 270 degree sweep for the LEDs. I put one on the 56 and it works pretty well once the sensor warms up.
     
  19. hawkeye649

    hawkeye649 1/2 ton status

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    [ QUOTE ]
    Yes, you can see results of rod and or jet changes. I had forgotten, but when I was tuning, I used a vacuum gage temporarily mounted in the cab so I could also see if it was a spring tension issue. For example, I tried the different primary springs from a kit I got from Edelbrock, but ended up back at stock with maybe one coil clipped off. Also, if tuning a Quad, you can see how the secondaries come in as well as the final WOT A/F ratio. Lastly, with a carbed motor, tune slightly to the rich side of the gage. Right on center (stoich) ran a little weak. Sweet spot with my combo was one or two segments up from center. Bottom line is that I get a dyno smog test each year, and it runs 1/4-1/3 of the specified limits for a 350 and it is a mild 383. Keep in mind that I am running a quench setup on this engine which helps keep detonation at bay even as you get pretty lean.

    [/ QUOTE ]

    Quench setup?? /forums/images/graemlins/ears.gif
     
  20. ntsqd

    ntsqd 1/2 ton status

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    [ QUOTE ]
    The wideband sensor would be great for tuning, but I think they were only made for one Honda and one supplier controls the whole supply, so the price remains really high. You could use a standard multimeter to do your tuning with one of those, though.

    [/ QUOTE ]

    There is a turbo VW application as well. Don't know the vintage.

    Here is a simple circuit for a 10 segment reader. Everything except the main chip is available from Radio Shack. Try Marvac-Dow or digi-key for the chip.

    [​IMG]
     

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