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Thread: Advanced Tables for Flex Fuel Content

  1. #1
    Join Date
    Aug 2012
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    Dayton, OH
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    Default Advanced Tables for Flex Fuel Content

    I was digging through my info from the Holley classes the other day and found a chart that showed the various stoichiometric values for gas, methanol, E85 & E100. After doing some math and dividing the AFR numbers, the difference between straight gasoline at 14.7 AFR and E100 at 9.0 AFR, you get a difference of 1.63. Shouldn't the offset in the Fuel Flow Multiplier look more like this?
    https://www.dropbox.com/s/hmbhcbhfag...24.54.png?dl=0

    This is the chart I'm referencing:
    https://www.dropbox.com/s/d92oqwm8g3...25.17.png?dl=0

    Secondly, is everyone leaving their Target AFRs from their gas tune alone and letting the Advanced Tables do everything? I've noticed that with 80% E content, my car idles much better with more fuel. Changing my idle Target AFR from 13.5 on gas to 13.0 on E80 made a world of difference. I know in the background, it's also adding .2 points to the AFR at 80% E content. I'm asking these questions because, as I understand it now, I'll be modifying the tune somewhat for the fuel change, which doesn't really make it seamless. I don't have a problem giving it what it wants, but I'm wondering if I'm going about it wrong.
    93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

  2. #2

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    Is your Base Fuel Table dialed in on E0 or E10? That will determine your zero point for the Fuel Flow Multiplier.

  3. #3
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    Default

    My pump gas tune was tuned on straight 93, no E content.
    93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

  4. #4
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    Default

    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  5. #5

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    Quote Originally Posted by Rick90lx View Post
    My pump gas tune was tuned on straight 93, no E content.
    Did you test it? I'd be surprised if it doesn't have 10% or so.

  6. #6
    Join Date
    Aug 2012
    Location
    Dayton, OH
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    Default

    I have two stations close to my house. One has no ethanol, the other has the standard 10%, according to the pumps.
    93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

  7. #7

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    You're still non-intercooled?

  8. #8
    Join Date
    Aug 2012
    Location
    Dayton, OH
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    Default

    Yep, as of now. I have a nice A/W setup, but haven't had the chance to get it installed.
    93 Notchback, 383ci SBF, Highports, 80mm turbo, custom cam, TH400

  9. #9

    Default

    Quote Originally Posted by Rick90lx View Post
    I was digging through my info from the Holley classes the other day and found a chart that showed the various stoichiometric values for gas, methanol, E85 & E100. After doing some math and dividing the AFR numbers, the difference between straight gasoline at 14.7 AFR and E100 at 9.0 AFR, you get a difference of 1.63. Shouldn't the offset in the Fuel Flow Multiplier look more like this?
    https://www.dropbox.com/s/hmbhcbhfag...24.54.png?dl=0

    This is the chart I'm referencing:
    https://www.dropbox.com/s/d92oqwm8g3...25.17.png?dl=0

    Secondly, is everyone leaving their Target AFRs from their gas tune alone and letting the Advanced Tables do everything? I've noticed that with 80% E content, my car idles much better with more fuel. Changing my idle Target AFR from 13.5 on gas to 13.0 on E80 made a world of difference. I know in the background, it's also adding .2 points to the AFR at 80% E content. I'm asking these questions because, as I understand it now, I'll be modifying the tune somewhat for the fuel change, which doesn't really make it seamless. I don't have a problem giving it what it wants, but I'm wondering if I'm going about it wrong.
    OK back from the dead. I'm going from 93 gasoline to E85. Regardless of where my base point will start depending on E content, shouldn't the scale be like the above poster explained? E85 requires 52% more fuel than straight gasoline, and 63% more fuel with E100. Wouldn't it be easier to just make the scale this way, and adjust your base start point?

    Another question probably already answered, but if you have your ideal 93 tune, should you still allow the ECU's Learn function to make corrections, or will this cause tuning issues?

    One more sorry, so as for the Target A/F Ratio table, in theory, if you just dumped in E85 with a gas tune, would the ECU automatically make changes and try to maintain Target AFR, being it's looking at Lambda and doesn't really care what fuel is burnt? Given that the Learn function was enabled and was high enough compensation.

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