2001-2005 Impreza WRX STi E85 Flex Fuel Conversion Kits
Increase the Horsepower of Your Turbocharged 2.0L 4-Cylinder by up to 20%
The 2001-2005 Impreza WRX STi was the first STi introduced directly to the North American auto market. Though its engine was a little smaller than the next generations of STi sports cars would be, this generation had the best racing suspension of all. It was very stiff and rigid which didn’t always make for a smooth ride but when it comes to cornering, the stiffer the better. No roll. No sway. No slop in the turns. Now imagine increasing that horsepower by up to 20% in an afternoon – by adding one of our plug-and-play E85 flex-fuel conversion kits engineered for your Impreza WRX STi.
The eFlexPlus and the eFlexPro are so easy to install that you can do it yourself in an afternoon and have your car running any mixture of E85 flex-fuel and standard gasoline the same day. Both come with a handy phone app that allows you to monitor the fuel mixture and switch between efficiency and performance profiles effortlessly. The eFlexPro comes with the additional eFlexTuner software that allows you to tune your turbocharged engine on any mixture of fuel above E50. Order one of these for your 2001-2005 Impreza WRX STi today and increase your horsepower from 261 even up to 335.
Installation
Plug&Play installation with some modifications - An experienced mechanic will install in 2-3h. For first time DIY installation, expect to double the time needed.
Technical specs
Make & Model
Subaru Impreza
Years
2001-2005
Engine
2.0l / EJ20K / EJ207
Power
261 hp
Always Optimized Fully Automatic Flex Fuel
Cooler & Cleaner Engine
Complete System, No Tuning Needed
Up to 20% Increase in Performance
Your Fuel System Verified
Dynamically adjust engine tune to match fuel
Available performance and eco tunes
Select performance or eco tunes via eFlexApp
Create and save custom dyno tunes
Pro grade eFlexTuner tuning software
+ What's included
Control unit (3” x 5 1/5” x 1” in)
Ethanol sensor
Wiring harness specific to your vehicle with an external temperature sensor (for 1-8 cylinders)
Two additional analog inputs that plug in to the engine’s own sensors (MAP, MAF, TPS or WBO) - included only in eFlexPro
Cable ties
Male fuel injector connectors
Fuel hose
Fuel line quick connectors
Fuel line disconnect tool
Hose clamps
Manual
+ eFlexApp
All eFlexFuel E85 kits operate via a wireless Bluetooth connection. This allows the eFlexApp to recognize the version of your E85 kit and monitor your engine in real-time while driving on E85, gasoline, or a combination of the two. With eFlexPro you can choose from six driving modes - three presets and three customizable ones. The app also lets you choose, monitor, and customize.
Features
Monitor ethanol content, fuel temperature, ambient engine temperature, injector duty cycle and cold enrichment, etc.
Choose your driving mode (Economy, Dynamic, Sport)
Display OEM engine sensor data: MAP, MAF, TPS, or WBO
Custom E85 tunes (Created with eFlexTuner)
1
3
+ eFlexTuner
eFlexTuner is a free PC software that connects to eFlexFuel kits via Bluetooth. Create your own custom E85 tunes and switch them while driving from the eFlexApp.
We always verify compatibility of the purchased product with the customer’s vehicle, so you don’t need to return or exchange your kit. If you must return or exchange your purchase, please contact us within 30 days of receiving your order. Your intent to return must be in writing, include a reason for return and sent to [email protected] Please include your reason for return/exchange.
The team at eFlexFuel will then issue a return authorization number (RMA) and shipping instructions. Please be advised – we are charging a $50 restocking fee. and be sure to buy insurance for the return shipment because we’re not responsible for returns that get lost or damaged in transit.
What's included in the eFlexPro E85 flex fuel conversion kit / Installation
Note: If your car is modified you can use E85 with eFlexFuel. If this is the case, please list all the main engine modifications on the checkout page. Our technical team will ensure that your setup is fit for E85.
* Power and torque increase depends on your engine technology and/or your custom built of the engine.
Not legal for sale or use on pollution-controlled vehicles
Attention Californian customers!
eFlexFuel products are not legal for sale or use on pollution-controlled vehicles in the state of California. Every reference to on road highway use on this site applies to other markets. We insist that our customers always make sure to follow their local rules and regulations.
SKU: U-EF-PLUS 
Always Optimized Fully Automatic Flex Fuel
Cooler & Cleaner Engine
Complete System, No Tuning Needed
Up to 20% Increase in Performance
Your Fuel System Verified
Not legal for sale or use on pollution-controlled vehicles