2021 Subaru Ascent Tuning

2021 Ascent_blog_cover

Subaru’s newest SUV, the 2021 Ascent, features a 2.4L direct-injected and turbocharged power plant that is ripe for turning up the wick.  We initially released support for the 2019 and 2020 MY Ascents a little over a year ago and are now excited to make tuning support available for the current model year.  Below, we’ll take a quick look at the Accessport, included Off The Shelf Maps, and power gains to expect.

Subaru Ascent Accessport (AP3-SUB-005)


The Accessport is the world’s best selling, most flexible, and easiest to use ECU upgrade solution for your Subaru Ascent. Unlock power hidden within the vehicle by replacing conservative factory settings with more aggressive calibrations. Follow our staged upgrade path with pre-loaded Off The Shelf (OTS) maps or use custom mapping for any modification level. It’s the last engine management solution you’ll ever need.  Simple ECU flashing with gauge package! The in-cabin mountable Accessport V3 has a large, full color, higher resolution screen which allows you to monitor up to six parameters in real time. Fully customizable from the look (multiple bezel colors), layout (set up race, street, or dyno gauge clusters), and mounting options (choose from 1,000s of standard vehicle mounts). And what’s looks without brains? More processing power, memory, and storage to flash faster while saving all of your maps and logs.


Off The Shelf Maps

Every Accessport will come with our Off The Shelf (OTS) Maps pre-installed and available to flash to your Ascent.  At this point, hundreds, if not thousands, of hours have been poured into understanding Subaru’s factory logic and ensuring manipulated calibration data does not negatively impact the car’s drivability.  We even put our development Ascent through it’s paces at Circuit Of The America’s in a good old fashioned torture test.

  • Stage0 v110.ptm
  • Stage1 87+ Economy Mode v110.ptm
  • Stage1 87+ v110.ptm
  • Stage1 87+ Valet Mode v110.ptm
  • Stage1 93 v110.ptm
  • Vehicle Anti-Theft Mode v110.ptm

Power Gains

For those looking to add a bit of power to their Ascent, two versions of our Stage 1 OTS map are available for the Subaru Ascent.  A Stage 1 87+ map is ideal for those who want to continue putting lower grade fuel in the tank but may want a slight increase in power.  This calibration can safely be used with any fuel ranging from 87-93 octane.  For those looking for a larger bump in power over stock, the Stage 1 93 map file provides even more power and torque gains across the board.  This calibration does require users to run 93 octane fuel to prevent more significant knock events.  During development, we discovered that Subaru truly calibrated the ECU to use an 87 octane fuel and testing with higher octane fuel while using the factory calibration did not impact the overall power of the engine, though it did clean up occasional minor knock events.

Stage1 93 Octane

Ascent Stage 1 Dyno

Peak Gains: +8% HP / +14% TQ

Max Gains: +21% HP at 4400 RPM / +21% TQ at 3800 RPM

Stage1 87+ Octane

Ascent Stage 1 Dyno

Peak Gains: +5% HP / +3% TQ

Max Gains: +9% HP at 4400 RPM / +9% TQ at 3800 RPM

Non-Performance Maps

In addition to the performance maps mentioned above, we are also including an assortment of non-performance map files that can be useful in various situations.

  • Stage0 v101.ptm
    • This map allows users to experience all of the Accessport’s functionality while retaining factory Subaru calibration data.
  • Stage1 87+ Economy Mode v101.ptm
    • This map file will give users the best potential fuel mileage when compared to the 93 and 87+ Stage 1 files.  *Actual results will vary
  • Stage1 87+ Valet Mode v101.ptm
    • Limiting requested torque and implementing a 2-stage speed limiter allows Ascent owners to prevent abuse of their cars in certain situations.  Throttle reduction past 60 MPH, fuel cut at 70 MPH.
  • Vehicle Anti-Theft Mode v101.ptm
    • This file will prevent the vehicle from starting and is ideal for use in situations of longer storage.

For additional information, visit the Map Notes Page.

If you have any questions, please feel free to reach out to our Customer Support team at 1-866-922-3059 or support@cobbtuning.com.

Stay Tuned.

Stephen Rudolph on January 8, 2021 says:

Will this work on a 2020 Subaru Legacy XT Touring? (Same engine as the Ascent.)

    Marshall on January 8, 2021 says:

    It will not. We are working on support for the 2020 Outback XT however it is not yet available.


Rich K on January 29, 2021 says:

Any 91 octane Stage 1 mappings (cali)?

    Marshall on February 1, 2021 says:

    Hey Rich,

    The 87+ map is appropriate for use with ACN91 octane fuel. We chose to simplify the map offering for Ascent and limit to two “performance” offerings, one being suitable for most available pump fuel, and one for higher quality 93 octane fuel.


Mike G on February 15, 2021 says:

Are there any plans to offer an Accessport for the Legacy XT trims? While obviously not exactly the same, the Outback and Legacy share the same platform and many of the same components. Even the owner’s manual lumps the two together!

Basically, if Outback support is on the horizon, will that mean the Legacy is not too far behind?

    Marshall on February 23, 2021 says:

    Hey Mike! From what we have seen, the Legacy and Outback XT use the same ECU ROM ID and thus will be supported together. We are still working on understanding some undesirable transmission behavior but hope to have some sort of news in the near future.


Anthony Gagnon on February 16, 2021 says:

When can I expect to have new software update for my 2021 Ascent. bought accessport a couple weeks ago and sent over a diagnostic…soo eager to get to tuning the subaru. please help!!!

    Marshall on February 23, 2021 says:

    Hey Anthony,

    We’re working on making support for the new 2021 Ascent ROM available this week! You will be able to perform a Firmware Update using Accessport Manager once released, I’ll make a note to email you once available.