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  1. #1
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    Need alittle help here please guys, forced induction air fuel ratio help needed

    ok guys,

    i need some help ive just installed the stack wideband gauge in my z4m VT2-500, on the recommendation of my tuner alot with boost and oil pressure.

    BUT i have literally no idea what AFR is, What my AFR is telling me and What if anything i should be looking for..........

    Can someone basically give me a detailed explanation on terms like AFR stoichiometric?

    If i run stoichiometric should this flash up 14.7 on my gauge indicating a non lean non rich situation?

    this is the gauge i have

    http://www.stackltd.com/instruments.html#Lambda

    if someone could take the time to look through the instructions provided on the above link id really appreciate some help to get this setup. my tuner told me ITS a must to have this gauge so i forked out the money and basically have NO CLUE what im looking at.....

    FI guru's please chime in!!!

  2. #2
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    Well my afrs are 14.-14.8 at idle/cruise of course it jumps around a bit.
    At WOT 11.3-11.8

  3. #3
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    You asking what afr means?

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    Click here to enlarge Originally Posted by BattaM3 Click here to enlarge
    You asking what afr means?
    He's about about AFR and how to read it / understand it. Basically, what he should be looking for.

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    Yea I figured that. I'm not good at explaining things. Didn't read his post correct first time.

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    Basically yeah i want to know the gauge is teling me, this is one area of FI i have no idea about and its very important.....

    Come on sticky hook me up ;-)

  7. #7
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    Click here to enlarge Originally Posted by beedub Click here to enlarge
    Basically yeah i want to know the gauge is teling me, this is one area of FI i have no idea about and its very important.....

    Come on sticky hook me up ;-)
    I'm helping Click here to enlarge Man I've got a ton of posts to read plus I'm trying to get a new website up. I edited the thread title to try to get you some help and I will check back in a bit if no one assists you.

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    2 out of 2 members liked this post. Reputation: Yes | No
    On any gasoline car, 14.7 is the stoich value of gasoline. So, for gasoline, 1 lambda = 14.7 Air to Fuel. When you're in a turbo S54 and wide open throttle you would expect to see something 12.0:1 or richer (smaller number). Its Air:Fuel. So if you run 14.7:1 you are running 14.7 units of air to 1 unit of fuel. When in boost making power, to run safe, you want to run only 12 units of air to 1 unit of fuel, or less. So seeing AFR from 11.0 - 11.8:1 would probably be ideal in an FI S54. When you idle and when you cruise down the highway part throttle the ECU will adjust fuel in and out to try and be economic, so it will cause the gauge to rock back and forth say 14.0 - 15.3:1 in and out, targeting somewhere in the middle.


  9. #9
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    ^ Solid and straightforward post there.
    Click here to enlarge

  10. #10
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    awesome thanks, guys :-)

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    Click here to enlarge Originally Posted by SSDD Click here to enlarge
    ^ Solid and straightforward post there.
    Just checked back to this, yep, agreed.

  12. #12
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    Awesome info here. Thanks guys.
    Click here to enlarge



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