Custom Tuning Adder – E85 Ethanol

Custom Tuning Adder – E85 Ethanol


This option is specifically for adding an additional tune for E85 Ethanol fuel. This is an ADDER meaning that you must have already purchased our custom tuning, in order to receive an E85 Tune based off of your Gasoline tunes.

Please read our important notes below regarding ethanol content in your fuel. If you don’t know what E-85 is, then this fuel may not be for you. You need to understand how E85 works and what it is.

Important usage tips for E85 Ethanol fuel

  • Our tunes are designed to run on gasoline, or on E85, but NOT a blend of the 2 fuels. Because the Air/Fuel ratio is drastically different between the 2 fuels, a blend will cause problems with the tune and drivability issues.
  • When switching between 2 fuels, you MUST drain all fuel from the tank before adding the next fuel type. Any residual in the bottom of the tank will throw off the tune from its accuracy. Run your fuel tank to Empty, and then fill completely up with the next fuel. And then drive it around for awhile before topping off again with the fuel, in order to ensure the old fuel is diluted out as much as possible.
  • This is the number one problem that customers report about drivability issues related to E85 use. Understanding how E85 works is important for understanding how to use its benefits.
  • Always use an alcohol tester to test every batch of E85 that you buy at the pump. It can vary from E50-E90, so you want to make sure you are somewhere close to E85, ideally no farther outside of E76-E86 or you may start to notice issues.
  • When you first switch fuels, remember that you may have added E85 in the tank, but the old fuel in the fuel lines and rails is still gasoline until you run it out. So if the car runs roughly at first, you need to clear out that old fuel before the car will get the fuel you put into the tank.
  • IF the car gets a Wrench icon on the dash display, it is in “Limp Mode”, and reduces throttle input and speed for safety. This is usually because of the % of alcohol in your e85 not matching your tune/calibration. If this happens, turning the car off and restarting it, resets this and should resume normal driving, but will likely occur again until the problem is corrected. The #1 reason for Limp Mode when using E85 is because your fuel blend in the car is NOT close to 85%. You must buy a $15 ethanol fuel tester to test the fuel in your car with each batch of e85 fuel you buy at the pump to ensure it is accurate. ($15-20 on Amazon) You can avoid this problem by buying race-blended e85 fuels like VP X85, which are already blended to exactly 85%. Pump stations have a wide variety of blends and are not always dependable. Your car is not a true “flex” fuel vehicle and in order to run E85, you must run a consistent blend that matches what your tune is set for.
  • We will NOT be able to help you diagnose the problem  or look at a datalog unless you can tell us the percentage of alcohol in your fuel because we won’t have any accurate data. You MUST test your fuel quality.

Related products

  • 2015-23 Mustang Convertible Rear Seat Delete


  • Shrader TUNING
    Shelby GT350 (2015-2020)


  • Shrader TUNING
    2015-2017 Mustang GT (Gen 2)


  • Shrader TUNING
    2018-2023 Mustang 5.0 (Gen 3)



Go to Top