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FF tune vs. 93 tune

Bluemustang

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Is the flex fuel tune running E a better performer than a straight 93 tune? I know that at least on the Lund FF tune, it won't advance timing beyond what a 93 tune does. So it won't allow more peak timing like an E85 tune does, nor will it ramp up timing like crazy down low like the E85 tune does.

But as far as 93 octane goes, not everyone's car is the same and not all 93 fuel is the same. So you may not always get the full timing advance that the 93 tune allows, just because the fuel isn't good enough.

I guess what I'm wondering is, will the flex fuel tune be a better performer (especially down low) than the 93 octane tune? I can see on my logs that I will hit the maximum base timing up top if I use ethanol on the flex tune. I won't get there running 93 octane. But in the lower rev range it's harder to tell.

I've been told that the flex tune is really a convenience tune, not an everyday tune, even though some people use it for that. I get less than stellar results on 93 octane for whatever reason - guess the fuel just isn't that good. Was thinking about using the flex tune even in the winter time, maybe like an E30 or E40 mix so I can better timing up top and down low. Does my thinking make any sense?
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beefcake

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flex fuel will maximize timing for your setup, and flex should allow for more timing,

the e85r however will ramp it in sooner..

for n/a cars we run flex all the time, unless we are on 100% e
 
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Bluemustang

Bluemustang

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flex fuel will maximize timing for your setup, and flex should allow for more timing,

the e85r however will ramp it in sooner..

for n/a cars we run flex all the time, unless we are on 100% e
Hmm, so you recommend flex all the time? Even though it is not as accurate?
 

FruityJudy

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Max timing on flex should be the same as max time on E85R tune as beefcake has stated, which will be higher than 93 on flex or 93 tune
 

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MaskedRacerX

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For me, even if running 93 on a FFT was slightly inferior, it wouldn't matter, I went with a Flex to accommodate the E fuel available here (not "pure" E85) and as a convenience factor in case I got into a situation where I couldn't get to some E, and didn't want to sit in a parking lot, maybe 2 hours from home, and reflash my car.
 

Zelek

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I'm about to go back to my flex tune here shortly after the last 4 tanks were E85. My 93 tune was my data logging tune. I don't notice much of a difference aside from the alch % learn that flex does. I figured flex may have a slight advantage if the alch % is actually higher in the gas, but I think the straight 93 tune already accounts for about a 10% alch mix?
 
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Bluemustang

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Yeah plan is to run the flex tune and run a little E. My car just doesn't perform that well on just 93 octane. The most peak timing I'll see is 27.5 before knock sensors start pulling timing. I've verified that it is not false as once ethanol is introduced on the FF or E85R tunes, it runs and no pulled timing.

I saw an interesting research article that talked about different %s of ethanol mix on volumetric efficiency. The article suggests that for N/A engines, E40 produces the largest increase in volumetric efficiency over gasoline. After E40 it starts to go back down. Boosted applications are different because the added knock protection of full E85 becomes more important.

https://www.researchgate.net/figure...ency-at-different-engine-loads_fig7_282877799
 

MaskedRacerX

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Bumping this to [re]ask for clarification:

93 on a FlexTune vs. 93 on a 93 spec tune, probably the latter? I ask because I've been having some issues running E, minor, but annoying, and I have both a Flex and a 93 tune loaded in my X4, I think I may just switch off of E for a while, assuming that fixes the issues.

Again, no E, just running 93 octane (good product from Sunoco), flex vs. 93 tune.
 

FruityJudy

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They are the same on 93 octane from what Lund has told me but the tuner would rather you run the dedicated 93 tune when on 93.

Now my question, my E85 is hand testing 77 to 79%. My Nguage on flex is only locking in on 67-69% (tried to get it to lock in higher several times). My STFT will be 2-4ish at idle or very light throttle thus getting my reading up to as high as 76% on nguage (not locked in), but when driving at anything over light throttle my stft will be -1 to -3 ish and bring it back down to mid 60s. My question is should I let it learn at idle or driving?
 

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BmacIL

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Bumping this to [re]ask for clarification:

93 on a FlexTune vs. 93 on a 93 spec tune, probably the latter? I ask because I've been having some issues running E, minor, but annoying, and I have both a Flex and a 93 tune loaded in my X4, I think I may just switch off of E for a while, assuming that fixes the issues.

Again, no E, just running 93 octane (good product from Sunoco), flex vs. 93 tune.
I switched back to my 93 tune because it has better drivability and crispness than the flex tune on 93. Flex is a neat novelty but I'm happier running 93.
 

50Mustang

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They are the same on 93 octane from what Lund has told me but the tuner would rather you run the dedicated 93 tune when on 93.
Just to piggyback on this, I've been told the same thing by other tuners; a FF tune will limit timing when running just 93, so a proper 93 tune will slightly outperform a FF tune when running just 93.
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