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.

• AEM 5 bar MAP sensor (reliable Manifold Absolute Pressure sensor)
• AEM air intake temp sensor DTM connector
• AEM 150psi fuel pressure sensor (Engine safety feature, allows ECU to compensate for drop in fuel pressure)
• 3 port electric boost control solenoid (ebcs allows ECU to control boost target, very important for engine safety) 
• AEM X series AFR gauge (used to provide a wideband AFR signal to the ECU for accurate tuning, CANbus and Analog outputs with LED display). 
• ID1050x WRX (Injector Dynamics 1050cc for WRX and STI)
• ID1300x WRX (Injector Dynamics 1300cc for WRX and STI)
• AEM in tank high flow fuel pump (e85/ethanol safe)
• Haltech Elite Etune
• Motec Etune Once all parts are installed we can provide a full custom E-tune for any build, mild to wild. All Etunes are done through emailing data logs and calibration revisions. 
• Get $50 off any Injector Dynamics order with coupon code: hohu50
• Get $100 off any ECU + Dash with coupon code: hohu100

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: