Is a E-85 tune a tune for pump E-85 or for E-85R? I'm curious on how they could make a tune for pump 85 not knowing the true E%.

 

The truck has sensors to find out the ethanol content of whatever you put in it. Then the computer plots the data for certain timing.

If you have a dedicated E85r tune, you better be testing the quality of the e85 your running.

 

Seems this same question comes up every year and the answer is always the same.

For what ever reason some tuners attempted to adapt a tune for engines not originally designed to run it. It's a bad idea considering all the factors that go into a vehicle designed to use it. If you have a flex fuel vehicle already (most 5.0 are) then just get any 93 race tune from the likes of 5*, MPT, etal.

That is what custom tuners from both 5* and MPT told me when I asked them this very question 6 years ago. They both told me the stock programming will handle the Ethanol content naturally and since most pump E85 is at least 95 octane, their 93 tunes will work just fine and you know what? They were right.

I've been running a 93 race tune from MPT for 6 years using E85. I and my truck both love the power.

 

Tuners have e85 tunes down perfect. Good tuners I should say. They won’t tune on the ragged edge for e85. Anything 70% up and you’ll be fine. Unless you tell your tuner to tune for e85 race fuel you’ll be fine with what your getting from the gas station unless it’s really junk fuel.

 

Agree

 

I run e85 in another vehicle with an ethanol-content sensor. I see variations from 65% in winter months, up to 80%+ in summer months. My Cobb AP automatically adjusts the tune (blend maps) in accordance with e content.

 

Ah. I didn't know that the tunes were set to be variable on e85. I was just looking at the octane rating of the tunes.
thanks

 

The state of Minnesota claims 108 octane.....tune for 105 and use the OAR ranging to get get max power when possible.