GR WRX NexGen Flex Fuel Installation Instructions
(315670, 324260)- NexGen Flex Fuel
2011-2014 Subaru WRX (GR)
Congratulations on your purchase of the COBB Tuning NexGen 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.
Parts List
324260- Flex Fuel Sensor to Fuel Rail Line Kit
315670 - Ethanol Sensor
Tools Needed
Sockets
3/8"
3/8" ratchet
3/8" 12" extension
3/8" 6" extension
3/8" Socket Swivel
3/8" 10mm socket
3/8" 11mm socket
3/8" 12mm socket
3/8" 10mm deep socket
3/8" 12mm deep socket
Hand Tools
Phillips head screwdriver
Flathead screwdriver
3mm Allen Key (included)
Wrenches
10mm combination wrench
TLDR Reference
Pre-Installation Steps
Inspect the new components included with the COBB kit. If anything appears out of place, please contact COBB immediately and do not proceed with the installation.
Park your car in a flat, level area and allow it to cool down all the way.
Discharge the existing fuel pressure from the system. It’s a good idea to consult the factory manual for OEM methods. One potential route if you feel it can be done safely, is to let the car idle, and then remove the 15a fuse for the fuel pump. (Consult your owners manual or fusebox for which fuse this is) This will allow the car to run for a few moments longer and then stall. While there will still be some residual fuel in the system, it won’t be under pressure so you won’t cause AS big of a mess. Set the fuse and fusebox lid somewhere safe for the time being. Make sure to turn the car off after it stalls!
Disconnect the vehicle's negative battery terminal first, then the positive battery terminal with a 10mm wrench or socket. Ensure no sources of spark or flame are present. Remove the battery from the vehicle.
With that you can loosen the two 10mm nuts on the hooks holding the battery in place, and remove the battery from the car to have more space available and access to where we’re going to make changes later.
Remove the existing fuel feed line, squeeze the tabs on the quick release fittings at the firewall and at the engine, and pull to remove each end, then pull the hose free from the center support and remove from the car.
Some of your intake will need to be removed. If using a COBB SF intake, you can get by with just removing the silicon piece going from the maf housing, to the turbo inlet.
Bench Pre-Assembly
Using the two supplied flat head screws and allen key, attach the flex fuel module to the bracket.
Flex Fuel Module Installation
Locate the bracket holding the power steering reservoir to the strut tower. You’ll loosen the bolt (and on some cars the nut on the right) holding the bracket to the strut tower using a 12mm socket.
Slide the right hand side of the module bracket over the stud on the engine side, then rotate it downwards until it’s behind the bolt on the outside.
Once the module bracket is snug behind the stock bracket, you can snug the bolts back down.
Flex Fuel Harness Installation
Starting on the passenger’s side, plug the supplied 6 pin deutsch connector to the module.
Working down the harness making sure not to route it too tightly between things as the engine will move. Unplug the factory connection from the TGV. There is a release to squeeze on the bottom side of the connector.
Plug the Flex Fuel harness into the TGV directly.
Now if you’re running it without the fuel pressure sensor, plug the flex fuel harness into the stock engine harness.
If you’re using the fuel pressure sensor kit, plug the flex fuel harness into the fuel pressure sensor harness, then the fuel pressure harness into the engine harness. If these are not done in the correct order you will end up getting error codes pop up.
The next plugs as you head down the harness will go to the electronic boost control solenoid (EBCS). These plug into the harness and EBCS to provide power for the flex fuel system. It's possible to get this unplugged without undoing the bracket from the intake manifold, but it can be easier to see what you're doing if you do remove the bracket and swing it away from the inlet.
These plug in similar to the TGV in that one connector plugs into the EBCS, and the other goes to the engine harness.You can either run your ethanol content and fuel pressure wires along the pcv hoses on top of the intercooler (in which case you’ll pull them out of the way for now, keep in mind you’ll need to trim zip ties every time you remove the intercooler) OR along the top point of the intake manifold and meet up with the MAP sensor harness.
Once your wires have made it to the driver’s side (USDM). Take a second (or several minutes for those of us with large hands) and remove the engine harness connector from the TGV. Once again, the harness will go in-between the engine harness and TGV. It’s usually easier to connect to the TGV first, and then the engine harness. You’ll also want to pull the brown ethanol sensor connector down there and the ground so you can route both under the battery cables and fuel lines to prevent chafing.
Pull the ethanol content sensor plug out underneath all the lines near where the battery tray was. It can get plugged into the ethanol content sensor.
Run the small ground wire underneath everything and up the back side of the fuse box to sit under the 10mm bolt sitting next to the main fuse box bolt. (the cover will need to be off to remove that bolt)
Ethanol Content Sensor and Fuel Line Installation
Remove the 10mm bolt holding the fuse box to the chassis.
Take the larger 90 degree end of the shorter hose and connect it to the left side of the ethanol content sensor (away from the bolt down strap and the same end with the electrical connector) Then make sure and clip the hose connector shut.
Now slip the ethanol content sensor with the blue fuel line and electrical connector attached, under the tab for the fuse box, (the bolt on the left) and tighten it back down with the factory bolt.
Now you can push the second longer fuel line with the large 90 degree connector onto the ethanol content sensor.
Make sure the shorter fuel line stays relatively close to the fuse box, and route it through the other cables and hoses and attach to the fuel line on the engine or the fuel pressure sensor adapter
The other longer hose (on the side further from the firewall) can go back to the fuel feed line on the firewall and get clipped shut.
Reinstall the battery at this time. Make sure it isn’t rubbing or putting pressure on the fuel lines.
Prime the fuel system by turning the car on (without starting it) and check for leaks. Repeat this a few times to make sure nothing is going to cause issues. Or tighten as needed.
If you’re leak free, go ahead and reinstall everything you took off in the reverse order of removal.
Flash an appropriate flex fuel tune and go out and enjoy!
Links
MAP Notes
Map Notes for 2009-2014 WRX MT North American and ADM Spec
Helps to figure out which map you should be on given the parts installed to your car
Related Parts
315660 - GR WRX Fuel Pressure Sensor Kit
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