Fuel Trim questions

[LOL WUT]

I am currently running a Lund flex fuel tune and it seems like every 3-4th fill up of E85 I have to do a KAM reset in order to get my LTFT to come back to earth. My STFT always seems to hover between -2 and 0. My LTFTs are usually around the same but every few fill ups the LT gets up to -9% or -10%. Cruising on the highway when things are good both LT and ST are between -2 & 0 when things are not great LT is between -2 & -10. If I get on the gas the LT starts moving closer to 0 as it should.

I have sent logs to Lund to which they say things look good.

The car is performing great and my pump E85 consistently tests out at E80. My mods are Lund tuned and LTHs. If it matters the car is a 2019, has 5,000 miles, 3,000 miles on E85 but I run 93 in the colder months.

Curious if there are any usual suspects I should look at or if this is considered normal behavior? Perhaps I am not letting each fill up “learn” the fuel content consistently enough?

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[Cory S]

LTFT's aren't much to worry about, and take awhile to stabilize anyway. I have 3 tunes with them shut off completely, and 2-3 with them active for passing emissions only.

 

[Zrussian13]

Sounds normal to me. Especially if you have a decent amount of highway driving. My ltft looks similar to yours due to the amount of off throttle coasting on my long commutes. When you drive it harder the ltft gets closer to the stft as it should because your not running it so lean any more.

 

[LOL WUT]

Sounds normal to me. Especially if you have a decent amount of highway driving. My ltft looks similar to yours due to the amount of off throttle coasting on my long commutes. When you drive it harder the ltft gets closer to the stft as it should because your not running it so lean any more.

Appreciate the comment, most of my driving the last month has been longer highway trips.

 

[Zelek]

If they told you the logs look good, then they are good. The flex tune is not meant to be driven around all of the time on even though many do. If you can, go full E85 and swap to the E85R tune. It works with anything above 75% alcohol content.

 

[LOL WUT]

If they told you the logs look good, then they are good. The flex tune is not meant to be driven around all of the time on even though many do. If you can, go full E85 and swap to the E85R tune. It works with anything above 75% alcohol content.

My fuel has been testing out consistently at E80 and the pump clearly has a disclaimer of “Minimum 70% ethanol content” so perhaps I will flip over to the E85R tune next fill up.

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