Lund flex fuel tune explained

[Ericlp]

So my car is tuned by Lund with a 91-93 tune, flex fuel and e85. I did the 2018 Mani swap. Currently I am on e85 but would like to switch over to 93 before storing it. I still don't entirely understand how their flex fuel tune works, otherwise I'm just going to run down to empty and switch straight over to the 91-93 tune. If someone could just explain how lunds flex fuel tune works that would be great

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[Cordero1]

Just fill up what you have with 93, run that out & fill it up with 93 again & so on. Shouldn't take much.

 

[rolfe.oliver]

The flex tune is a convince and to be used as a transitional tune. For example, if you are on 93 and want to fill up with E85, you will run your tank down as low as possible, fill up with Ethanol, flash the flex tune, and then watch your Alc. % as the Adaptive Octane "learns" the % of E in your tank. The flex tune is best used while the remaining 93 is still in your fuel lines, rails, etc, and before the E fully mixes in. The procedure would seemingly be the same when going form E85->93. Once it seems the 93 is fully mixed in, that is when I would go back to the 93 only tune.

Perhaps Nardi can chime in if this is misstated, but this is my understanding of the Lund Flex tune.

 

[Ericlp]

The flex tune is a convince and to be used as a transitional tune. For example, if you are on 93 and want to fill up with E85, you will run your tank down as low as possible, fill up with Ethanol, flash the flex tune, and then watch your Alc. % as the Adaptive Octane "learns" the % of E in your tank. The flex tune is best used while the remaining 93 is still in your fuel lines, rails, etc, and before the E fully mixes in. The procedure would seemingly be the same when going form E85->93. Once it seems the 93 is fully mixed in, that is when I would go back to the 93 only tune.

Perhaps Nardi can chime in if this is misstated, but this is my understanding of the Lund Flex tune.

Ok so basically just run the flex tune until afrs are back to 14s for the 93 tune then switch off flex?

 

[rolfe.oliver]

Ok so basically just run the flex tune until afrs are back to 14s for the 93 tune then switch off flex?

In theory yes, but if you are relying on the digital AFR gauge, that is inferred and not 100% accurate.

 

[drive_55_not]

Ok so basically just run the flex tune until afrs are back to 14s for the 93 tune then switch off flex?

You're running a Flex Fuel Tune, fill up with 93 and store it.

There's no reason to switch to a gas tune unless you just want to practice switching tunes.

Otherwise why did you waste money on the FF tune?

./

 

[Duston@Lethal]

The flex tune is a convince and to be used as a transitional tune. For example, if you are on 93 and want to fill up with E85, you will run your tank down as low as possible, fill up with Ethanol, flash the flex tune, and then watch your Alc. % as the Adaptive Octane "learns" the % of E in your tank. The flex tune is best used while the remaining 93 is still in your fuel lines, rails, etc, and before the E fully mixes in. The procedure would seemingly be the same when going form E85->93. Once it seems the 93 is fully mixed in, that is when I would go back to the 93 only tune.

Perhaps Nardi can chime in if this is misstated, but this is my understanding of the Lund Flex tune.

IMO you hit the nail on the head. Like anything else that is the best of both worlds, the flex fuel tune will hapilly run and account for any amount of E you'd like to put in. But it may have a few hairs less performance than a true E85 tune.

 

[LOL WUT]

Like others have said, load the flex tune. If you’re low on fuel fill up with 93. If you have E85 still in the tank put 93 in, doesn’t matter if you have a half tank of E85 or more. Flex tune will work with any combination of fuels.

While the general consensus is to not store with E85 in the tank, there are numerous people who store every winter with E85 and have no problems at all.

I wouldn’t overthink it, regardless, it’s a simple process.

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