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Why the Cobb AP Should Be Your WRX’s First Modification

October 30th, 2023 | 4 min read

By Alan Jackson

Modified Subarus have been around for quite some time now and fortunately for our generation, modifying them keeps getting easier and easier. The Subaru WRX and STI are great cars out of the box but if you're reading this, you are probably itching to modify yours. In the world of 2015 and newer Subaru WRX mods, there are plenty performance parts to choose from.

A little over a month ago, I picked up my second Subaru. My first was a 1996 Impreza Outback Sport and my second/current being a 2016 WRX. Like a good amount of other WRX owners out there, I had to modify my car to give it a little more personality and performance. To start, I picked up a Cobb Accessport and started down the road to tuning and upgrades.



What is a Cobb Tuning AccessPort?

The AccessPort is an ECU flashing tool that also doubles as a multi gauge display. It has a large color screen and many features that allow you to have a more in depth understanding of exactly what is going on with your car, mainly the engine. It’s the world’s most flexible and easy to use ECU flashing device for your Subaru.  It can read values such as boost pressure, air/fuel ratio, knock retard, ignition timing, and many more.

How does it work?

The AccessPort plugs into the OBD2 plug located below the driver's side dash area.  Once plugged in, you can switch maps or just leave it plugged in while you drive to monitor the ECU functions associated with the various sensors around the car like the O2 sensor (AFR), MAP Sensor (Boost Pressure), etc. You can also flash maps and leave it unplugged if you don't have the need for active monitoring. The maps stay on the vehicle.

Why_the_Cobb_AP_Should_Be_Your_WRXs_First_Modification_3-1 Why_the_Cobb_AP_Should_Be_Your_WRXs_First_Modification_16-1


Already have an AccessPort (or already know why you need one)?  Check out more bolt-ons and easy upgrades you can do to your WRX FA20DIT to give it some more go.>>>

Why do you need it?

Everything you change or modify in relation to engine performance on your Subaru affects the airflow and/or fuel that goes into the engine. Although easy to learn about, changing these things is a delicate art. If you install an intake that will help to get more air in, the car will need more fuel. Most modern ECUs understand small changes and make compensations based on them. But larger changes might make the ECU misunderstand what's actually happening. Using this as an example, without this added fuel you will run lean. The unlikely, worst case scenario is your engine suffers severe damage. A much more likely scenario is your car might lose fuel mileage or just not run very smooth.

Here is an example of what a typical dyno plot will look like after you flash the ECU with a Stage 1 OTS map.  This is on a completely stock VA WRX with no modifications other than the AccessPort.  The engine picked up a peak difference of +25hp and +14tq!  In addition, you can see the torque curve (dotted line) hold a higher amount of torque through almost the entire RPM range which is VERY noticeable while driving the car.  This is really what makes the car come alive.



How does it know what parts are on my WRX?

Cobb Tuning built a bunch of off-the-shelf maps that cover a wide range of mods. These OTS maps will make tuning your WRX easy and will allow you to install pretty much all the major bolt-on parts you could want without having to get a custom tune. This will save you a considerable amount of time and money.  The tunes are downloadable through Cobb's website and the most current maps are preloaded onto the AccessPort before you get it.  If there are ever any updates to specific maps, you can download them for free from Cobb's site and upload them to your AccessPort, then your car.

Here is what the typical process of flashing your ECU looks like.













My own experience...

Starting off with my Accessport, I didn’t immediately flash a higher performance map.  This way, I could get some datalogs that show how it performs from the factory. Then I flashed the stage 1 OTS Map and immediately picked up 25whp according to virtual dyno. Aside from the power gains, drivability is certainly improved and I am thrilled with the power delivery up top. The car is still all stock aside from the tune.

One of the first things I noticed was how the factory tune allows the car to run lean for a bit into a wide open throttle pull before going pig rich. This is not ideal from a safety standpoint though I’m sure it improves emissions. With the stage 1 tune flashed, the throttle response is now much smoother and more predictable. I love the way the car behaves now.


What's next?

For many people, flashing OTS maps is as far as you need to go. However, a handful of modifications later, you'll start to realize the OTS maps are only built for a couple mild modifications. This is where the AccessPort really starts to shine. I will be tuning this car myself so when I put on things like a 3-port boost controller, the AP gives me the ability to make custom changes to my tune using a computer and their back end software (only available to Cobb Pro-Tuners). All the important metrics mentioned before like AFR, boost, timing, etc. are all able to be fine tuned based on what the car responds to and what limits I feel comfortable pushing. This obviously requires a professional, like myself, but it's all because of the AccessPort that we're able to comfortably modify the car without worrying about how poorly it might be running. We can make it run how we want and use the datalogging capabilities to monitor the effect of our changes.

This is why the AP should be the first mod you get for your WRX. It's infinitely scalable. You can use it as the only modification you ever get or you can continue to use it in different ways as you keep modifying your FA WRX. Whether it's a mild 350whp stock motor daily driver or a fully built, 600whp, huge turbo setup, the AccessPort makes it all flow smoothly.

This post was originally published in January, 2015 but has been updated to reflect current parts and accurate information!