Flex fuel tune review so far

Discussion in 'V8 5.0L Engine / Mods: Bolt-ons, Exhaust, Tuning' started by stangman638, Mar 3, 2019.

  1. stangman638

    stangman638 Well-Known Member

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    So far, it's underwhelming. I can honestly say I don't feel much difference between stock and the flex fuel tune while running E85. I have not tried the straight E85 race tune. Ethanol content here in the winter is really about E60ish. So that will have to wait for summer. Some issues I experienced.

    After initial startup in the morning, started OK in 35 degree temps, as I drove up a slight hill, car sputtered and stalled, it restarted right back up again no problem.

    Sometimes on shifts, I'm guessing rather 1-3 or 3-4 gears (auto) car feels like it wants to surge and bucks for a quick second. However, doesn't happen often and when it does, it seems to be when I press on the gas, after making a complete stop, ie stop sign or traffic light.

    I do know the straight E85 will be much better, however, I believed the car on E85 with a flex would have felt stronger over a straight 93 tune.I don't think it does.

    Anyone else experience this?
     
  2. AZ18yote

    AZ18yote Well-Known Member

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    Here in AZ we dont have straight e85 just flex fuel which is about e54. On my flex tune it's a night and day difference from 91 octane. Pulls much harder , feels much more alive, even in 120 degree temps outside. Cold starts are more tame than 91 as well so just added bonus.

    How many miles on e have you gone? What is your AFR reading? Did you try a KAM reset as well?
     
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  3. VikingJoe

    VikingJoe Well-Known Member

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    My 93 race tune is a crazy difference from stock and the E85 race tune is even better. My car frikin' loves E85.

    From everything I have seen, the flex tunes are not meant to be aggressive.

    As for the sputtering and stalls at startup, that is normal when the car is cold. Sometimes it happens, sometimes it doesn't. But once the car is warm it is never an issue.
     
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  4. Bluemustang

    Bluemustang Well-Known Member

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    Something doesn't sound right. It should definitely feel stronger with ethanol on the FF tune.
     
  5. Zelek

    Zelek Well-Known Member

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    E85 race tune will have a lot stronger mid range, but both the flex and e85 tunes will have similar peak HP. It sounds like something isn't right.
     
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  6. OP
    OP
    stangman638

    stangman638 Well-Known Member

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    Dunno, I think it would but then again Alex from Lund points out in a vid if you have good 93 octane in your area you may not see much difference on a flex tune.
     
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  7. Zelek

    Zelek Well-Known Member

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    Is that in regards to comparing a 93 octane tune versus running 93 octane on the flex tune? There isn't going to be much of a difference at all between those. You should feel a pretty good difference between running E85 on flex versus a straight 93 tune on 93 octane gas. Flex isn't near as aggressive as the straight E85R tune from Lund. Where you will see a lot of power is up top with flex.

    I'm about to fill up on E85 for the very first time with my new flex fuel tune from Lund. I'll let you know how it goes. I've been running their 93 octane tune for well over a year so I'll be able to tell right away.
     
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  8. 1badrz28

    1badrz28 Well-Known Member

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    The bucking is common at throttle tip in(both stock and certain tuned variances) . Add the straight e85 tune and the bucking should remove itself with the additional timing added down low.
     
  9. TrevorGT

    TrevorGT Well-Known Member

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    Like others said, running straight E85 on my flex tune is night and day different over 93. Yours should be also unless it’s the blend of E85 your getting.
     
  10. Zinc03svt

    Zinc03svt Well-Known Member

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    Lol...
     
  11. Andy13186

    Andy13186 Well-Known Member

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    I noticed a big difference between stock tune on 93 and the pbd 93 tune, but the difference between the pbd 93 tune and the e85 tune didnt seem that big to me.
     
  12. scottycameron

    scottycameron Well-Known Member

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    My seat of the pants experience on a 1-11 dial (mine goes to 11) the stock tune is about a 4, the flex is about a 7 and the E85R is 10.5.

    The flex tune is a compromise and nice bump from stock. Enjoy it for what it is and then wait for the fun to begin with the E85 tune, it's as bonkers as can be for a N/A car. E85R in track mode is a hoot...
     
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  13. Zelek

    Zelek Well-Known Member

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    I just filled up on E85 last night and loaded my flex fuel tune. All I can say is, wow.... There is a huge difference in power and the car feels different during shifts. Almost feels as if it's running cleaner.

    My first WOT pull to 7700 rpm put a smile on my face. If you can't tell a difference with a flex tune and E85 in the tank, something is seriously wrong.

    It took me about 15 minutes to get to 83.5% on my alch% idling and neutral rev hanging after filling up and following Lund's learn process.
     
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  14. OP
    OP
    stangman638

    stangman638 Well-Known Member

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    KAM reset did the trick, no more bucking, felt better overall.
     
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  15. StangSteve

    StangSteve Well-Known Member

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    How is the 93 race tune? How much different over stock and could this be a DD tune? Who did you get it from? Thanks.
     
  16. Bluemustang

    Bluemustang Well-Known Member

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    This is probably more indicative of the limitations of the flex fuel tune. When running the flex tune, I found myself having to do a KAM reset every 1-2 months as the AFR values would start to drift over time.

    The flex tunes are for convenience... You can benefit from having ethanol in the tank, but the 93 and certainly the E85R tunes are different. I notice the 93 and E85 to be more crisp feeling.
     
  17. Zinc03svt

    Zinc03svt Well-Known Member

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    Guilty! I’m a Corniholic.
     
  18. TRPCANA

    TRPCANA Well-Known Member

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    Hopefully you get it worked out OP, for myself the flex tune is just fine, has same max HP potential as the E85R at WOT so you should really only possibly feel let down in the partial throttle but for myself i dont have this issue. The E85R however is a maxed tune which you will notice results. Another thing to bear in mind is you arnt the first person to report this, but just because it doesn't feel faster doesn't mean that it isnt.
     
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