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Thread: What should the AFR be under wide open?

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    Lifetime Member mvvette97's Avatar
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    Default What should the AFR be under wide open?

    2000 ta with ported heads and cam. on the wideband in the car it's between 12.9 to 13.1. Is that a little lean or about right? I'm not sure how to change it if it needs changed. What do ya think?

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    Generally speaking, 13.0 seems to be the universal target for N/A application with typical compression ratio's. FWIW, I noted very little change in output at the dyno with my car when running as rich as 12.7 vs. as lean as 13.4, so I shoot for 12.7-12.8 myself, rather leave it a little on the fat side and have a slightly larger 'insurance gap'.. just in case.
    Dave
    -'07 Acura TL Type-S
    -'07 Honda Ridgeline RTS
    -'00 Pontiac Trans Am WS6

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    Joe (Moderator) joecar's Avatar
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    Those ranges are good... typically the richer side of those may offer some protection from knock as Dave said.

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    Member Spindoctor's Avatar
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    Quick ref AFR values:
    These are for gasoline cars running a stoic of 14.65:1 as Lambda
    Other fuels will vary!

    15.6:1 for best mileage
    14.6:1 for best emissions
    13.6:1 for best lean torque
    12.6:1 for best rich torque
    11.6:1 for easiest ionization of the spark gap. I use this when boosting beyond a coils ability to fire the plug at leaner mixtures until a better system can be installed. It is a helpfull ignition diagnostic tool for those high load misfires- if the car runs better at 11.6:1 then you have too weak of a secondary system to ionize the gap at those loads.
    So then close up the gap, get better coils or (dare I say) lower the load.
    Hope this helps.
    Last edited by Spindoctor; September 17th, 2008 at 11:49 AM.
    Thanks in advance- The Spindoctor (Tim H)
    Back ground-Mustang AWD500 Dyno- Over 500 tunes on systems including: Autronic, MoTec, AEM,COBB,Haltec, Electromotive,Greddy, Microtech (to name just a few)and now EFI Live!

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    Senior Member Sid447's Avatar
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    Quote Originally Posted by mvvette97 View Post
    2000 ta with ported heads and cam. on the wideband in the car it's between 12.9 to 13.1. Is that a little lean or about right? I'm not sure how to change it if it needs changed. What do ya think?
    12.7 to 12.9 would be "safer" without being too rich.

    Change this on {B3618} PE Modifier Based On RPM (AFR) table.

    Ideally richer to peak torque then slightly leaner above, e.g 12.7 to 4800 then 12.85 or so above.

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    Lifetime Member mvvette97's Avatar
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    Quote Originally Posted by Sid447 View Post
    12.7 to 12.9 would be "safer" without being too rich.

    Change this on {B3618} PE Modifier Based On RPM (AFR) table.

    Ideally richer to peak torque then slightly leaner above, e.g 12.7 to 4800 then 12.85 or so above.
    Here is a copy of my tune It's already set to 11.7 all the way down.
    Attached Files Attached Files

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    Senior Member Sid447's Avatar
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    Quote Originally Posted by mvvette97 View Post
    Here is a copy of my tune It's already set to 11.7 all the way down.
    Assuming your WBO2 is working correctly, you need to do some auto-ve tuning to adjust the mixture.
    I see your IFR table has been adjusted, and the only change to your VE table is to make it 17% weaker(?) around the idle/low rpm area.
    Post up some logs for the guys here to have a look at.
    I think you are running too weak and this should show in your STFT's (and LTFT's).

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    Lifetime Member mvvette97's Avatar
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    I need to figure out how to hook my wideband to the interface cable so I can log with the wideband

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    Senior Member Sid447's Avatar
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    As a suggestion,

    run your car in open-loop in the meantime. At least you'll have actual afr's close, or the same as commanded.

    To help, here is a stock factory untouched open-loop tune for a stock -A4 car (auto) with the same OS as yours. Compare it with your stock tune to see exactly which fuelling parameters you need to set.
    Though I wouldn't run the same {B3605} as this tune has.
    Attached Files Attached Files

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    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by mvvette97 View Post
    I need to figure out how to hook my wideband to the interface cable so I can log with the wideband
    MV,

    Do you have FlashScan V1 or V2...?

    With V1 you connect wideband analog output to V1 analog input (AFR signal and signal ground).

    With V2 you have a choice:
    - analog, same as V1;
    - serial/digital if supported by wideband and/or FlashScan (need a "special serial" cable from TAQuickness);

    Which wideband do you have...?

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