Cobb STi & WRX Flex Fuel Update:

The Cobb Accessport has proven to be a powerful, flexible, and easy to use ECU tuning option the Subaru community. After years of development and use Cobb has announced Flex Fuel support for Subaru WRX and STi has been removed. Please see our Cobb Green Speed update article for details. For those looking to retain flex fuel support please have a look at out Motec, Haltech, Link and Emtron ECU packages listed at the end for this page. Please note all of these ecu options are for off road motorsports use only.

ID2600xds flex fuel tune

Why Do you need Flex Fuel or Ethanol?

Compared to standard pump fuel, the higher ethanol content in ethanol blends such as E85 provide a substantially higher effective octane rating. The octane rating of a fuel indicates its ability to resist detonation. This added resistance allows tuning to be more aggressive through timing and boost, yielding greater horsepower/torque output. These factors combined make for an ethanol/gasoline fuel blend with more power potential over the standard pump gasoline. With an active Flex Fuel system, a vehicle’s ECU is able to seamlessly blend calibrations required for any blend of Ethanol/gasoline. Using an ethanol content sensor and fuel pressure sensor the ECU can see the exact ethanol/gasoline blend (displayed as % via AP) as well as fuel pressure. Both these bits of data are extremely helpful to the tuner as well as the ECU’s ability to run in “closed loop” system, based on the 2 new fuel system sensors readings.

Injector Dynamics Sizing Subaru WRX & STI:

These are the only injectors we recommend using for any flex fuel or E85 powered WRX or STI. Injector Dynamics are designed specifically for alcohol and gasoline based fuels.

  • ID1050x STI & WRX (these are perfect for anyone looking to make 350-450whp)
  • ID1300x STI& WRX (these are perfect for anyone looking to make 450-650whp)
  • ID1700x STI& WRX (these are perfect for anyone looking to make 550-850whp)
  • ID2600xds STI& WRX (these are perfect for anyone looking to make 750-1300whp)

This means you can now safely run any blend of ethanol/gasoline and your ECU will know exactly how to handle the blended fuel. In the past we would normally use 2 different maps; 1 map for gasoline and 1 map for E85. While this works well it does not allow for any “blending” of the gasoline/Ethanol. Using the Flex Fuel kit with Ethanol content and fuel pressure sensors you can now simply use 1 Flex fuel calibration for any gasoline/ethanol blend resulting in more HP and Torque along with un matched reliability. Now that you can safely top off your fuel tank with whatever fuel is available you will never need to stress about which gas station you need to stop at again.

Subaru Tuning options post Green Speed update:

  • WRX Etune: Cobb AccessPort, custom tune for any WRX on AP. Bolt on mods to fully built race cars supported using the Cobb Green Speed Updated software.
  • STI Etune: Cobb AP protune, custom tune for your STI’s AP. From bolt on mods to fully built race car using the Cobb Green Speed Updated software.
  • Subaru WRX and STI Haltech Elite ecu packages: VE plug n play adapter harness delivers a clean/simple plug n play harness to adapt your EJ25 powered Subaru to run the Haltech Elite 2500 ECU. 
  • Subaru STI Motec M150 ecu kit: Plug n Play harness + ECU using the best motorsports grade ECU available. If you have a serious build this is the ECU package for you.
  • STI EMtron ECU packages: Please give us a call for the latest Emtron ECU packages and pricing. These all NEW plug n play kits for 2015+ sti are not yet listed for sale on our website so you will need to call or email.**
  • STI Link ECU Plug and Play for 2007-2011 USDM STI & WRX using Denso ecu. 
  • Cobb Tuning Carbon Fiber intake for 2015-2022 STI, Cobb Redline series

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