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Thread: AFR for todays Car with ethenol?

  1. #1
    Advanced Tuner Braciole's Avatar
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    AFR for todays Car with ethenol?

    Im well aware 12.7-13.0 is the sweet spot for NA LS cars, But is anyone taking into consideration the fact that Ethenol is in almost all gas sold?
    With this in mind is anyone leaving their cars or the cars they tune a little Fatter?
    Thanks for any imput
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    Senior Tuner Frost's Avatar
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    Your wideband is actually logging lambda and calculating AFR... 0.86λ is shown to you as 12.7-ish:1 regardless of ethanol content. That can make it easier to think about. Additionally, as ethanol content rises, the sweet spot for WOT AFR loosens up a shade as well.
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    Quote Originally Posted by Frost View Post
    Your wideband is actually logging lambda and calculating AFR... 0.86λ is shown to you as 12.7-ish:1 regardless of ethanol content. That can make it easier to think about. Additionally, as ethanol content rises, the sweet spot for WOT AFR loosens up a shade as well.
    Weird. I have the NGK AFX and outside of stoich, I show the AFR/Lambda I'm targeting for my specific fuel

    For instance, I'm targeting .85 Lambda with a 14.13 stoich value for the E10. My wideband outputs ~12 AFR, not ~12.5 as you would suggest.
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    Senior Tuner Frost's Avatar
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    It depends on what the WB manufacturer wants to call stoich though... You can't change what it considers to be stoich with that unit. Some people gripe about that with the AFX.
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    Quote Originally Posted by Gh0st View Post
    Weird. I have the NGK AFX and outside of stoich, I show the AFR/Lambda I'm targeting for my specific fuel

    For instance, I'm targeting .85 Lambda with a 14.13 stoich value for the E10. My wideband outputs ~12 AFR, not ~12.5 as you would suggest.
    Are you sure? I have several AFX's and no matter what fuel, they show around 14.5 in closed loop.

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    stiotch for afx is 14.56

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    Quote Originally Posted by backchannel View Post
    Are you sure? I have several AFX's and no matter what fuel, they show around 14.5 in closed loop.
    Quote Originally Posted by carlrx7 View Post
    stiotch for afx is 14.56
    Yep, I'm talking about outside of stoich. Frost said .86 Lambda will show up as 12.7 no matter the ethanol content of the fuel, which is something I don't experience.
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  8. #8
    Senior Tuner DSteck's Avatar
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    I think there's still a lot of confusion on what lambda is and how a wideband really works.

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    Quote Originally Posted by Gh0st View Post
    Yep, I'm talking about outside of stoich. Frost said .86 Lambda will show up as 12.7 no matter the ethanol content of the fuel, which is something I don't experience.
    My comment was to show that the afx just reads lambda [at stoich or elsewhere] and then converts the display to afr.
    You haven't explained how you are testing to show this is not the case.

  10. #10
    Advanced Tuner Braciole's Avatar
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    So nobody is leaving their tunes a little fatter?
    2007 C6 coupe LS3 416 6 speed mn Z51 3LT
    Vararam Snake charmer 160 Stat
    Kooks 1 7/8 headers with jet hot
    Fast 102 ported intake 102 TB RPM Level 5 T56
    MGW short throw ZIP 4.10 Severe Duty rear
    RPS TWIN DISC CARBON CLUTCH CCWs ele wp
    RPM LEVEL 5 TRANS W/HARDENED OUTSHAFT
    http://www.youtube.com/watch?v=PtOPy_lp2QY

    10.66 1.47 60ft 133+mph

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    Quote Originally Posted by Braciole View Post
    So nobody is leaving their tunes a little fatter?
    I run around .85 Lambda, so yes, I am running "fatter".
    2012 Chevy Cruze A6 1LT RS

    Formerly - 2004 GTO, 2002 Z28, 2007 Colorado, 2008 Silverado

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    Quote Originally Posted by backchannel View Post
    My comment was to show that the afx just reads lambda [at stoich or elsewhere] and then converts the display to afr.
    You haven't explained how you are testing to show this is not the case.
    I know this, I am not arguing you.
    2012 Chevy Cruze A6 1LT RS

    Formerly - 2004 GTO, 2002 Z28, 2007 Colorado, 2008 Silverado

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    Quote Originally Posted by Gh0st View Post
    I know this, I am not arguing you.
    oops - guess I misread

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    Quote Originally Posted by Gh0st View Post
    Weird. I have the NGK AFX and outside of stoich, I show the AFR/Lambda I'm targeting for my specific fuel

    For instance, I'm targeting .85 Lambda with a 14.13 stoich value for the E10. My wideband outputs ~12 AFR, not ~12.5 as you would suggest.
    The actual AFR for regular gasoline at .85 Lambda is indeed approx. 12.5.
    For E10 at .85 Lambda it is indeed approx. 12.0.