Congratulations on your purchase of the COBB Tuning Flex Fuel kit! The following instructions will assist you through the installation process. Please read them BEFORE beginning the install to familiarize yourself with the steps and tools needed. If you feel you cannot properly perform this installation, we HIGHLY recommend you take the vehicle to a qualified and experienced automotive technician.
IMPORTANT! Installing this kit will require custom tuning or utilizing an appropriate Stage Power Package map if you have a matching mechanical configuration. Please consult with COBB or an authorized ProTuner in your area.
Part List
Tools Needed
Important! Before removing your fuel line, make sure to discharge existing fuel pressure from the system. Failure to do so can result in fire, property damage, and/or death!
With the power unhooked go ahead and remove the stock feed and return lines. You'll need to use a 5/16 fuel line quick-disconnect tool, simply press it in the end to release the lines. While not strictly necessary, removing the return line can give you more room to more easily access the feed line.
The color of the sheathing on the hard line at the firewall is not consistent across all year/models. |
Notes on Flex Fuel Kit Hose Installation.
The COBB Flex Fuel Sensor installs between the manifold side fuel line connector and the regulator. In our example we're still using the factory regulator so we'll be installing the sensor on our feed line. Our Flex Fuel Sensor and/or Fuel Pressure sensor do not restrict fuel flow and will not cause any hindrances. It's also mandatory that you install either sensor pre-regulator to ensure accurate readings. The flow of fuel is as such:
We have included variety of fuel line connectors for a variety of applications, all of the factory fuel line connections are 5/16" while the connections on the ethanol content sensor are 3/8". The stock fuel lines have dampers built in however those are no longer necessary as the rubber line itself provides a dampening cushion unlike the relatively hard plastic of the old fuel lines.
It is absolutely critical that hoses are routed away from heat sources and protected from rubbing on anything. It's usually best if they're held down by zip ties or the factory brackets as damage to the lines can cause a leak or fire. In many cases adding some type of sheathing can add to the longevity of the hoses. Make sure all of the lines have some slack to allow for engine movement to avoid putting undue strain on the lines. |
Start out by adding your connectors loosely to each end of the line you're doing at that time, then measure the distance, sometimes using a piece of string can help get an idea of routing, but it's usually best to use it with an actual piece of hose to get an idea of how far it can be bent without kinking and how it will fit with everything else. The white connectors are 5/16" for the stock fuel lines and the blue connectors are 3/8" for the Ethanol Content Sensor.
The COBB Flex Fuel Module is designed to be bolted to the inter-cooler support bracket and plugged into the COBB Ethanol Sensor, in-line with the factory Rear O2 sensor and Tumble Generator Valve (TGV).
The Rear O2 connector obtains 12V power, and does not alter the O2 sensor signal going to the ECU. The TGV connection allows the motor signals to pass through for those still using the factory TGV's, however the feedback normally used to check TGV position is used to transmit Ethanol content data to the ECU (Engine Control Unit).
Mounting location may vary by customer/ installer preference, however it is recommended to seal any un-used connections from water intrusion, ideally by using the proper connector mate and using plugs to seal the mating connector.
Ethanol Sensor Input Selection = TGV Left
Sensor calibration:
0.5 V = 0% Ethanol
4.5 V = 100% Ethanol
COBB Product Install Instructions for Subaru Vehicles
Main Installation Instruction Repository for Subaru Parts