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 [email protected].

Stay Tuned.

34 responses to “2021 Subaru Ascent Tuning”

    • 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.


  1. 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?

    • 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.


  2. 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!!!

    • 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.


  3. Not looking to increase power/speed but want to smooth out the transmission in town. Also, it seems to rev up to 2500-3000 rpms on an incline going 30-45 mph and drives me crazy! Will this help??

    • Hey there! We don’t manipulate anything specific to transmission behavior so I can’t say with certainty that a tune would solve your uphill concerns. With that said, power delivery and throttle pedal sensitivity is much more linear with our tunes.


    • Hey Ben,

      We do not currently have an ETA for Outback XT tuning. Increasing power over stock has caused some undesirable transmission behavior that we did not encounter with the Ascent. We are currently looking into the CVT controller and hope to have more news in the coming months!


      • I was wondering if there has been any progress on the Outback/Legacy XT tuning? Last update you guys were looking at the CVT controller to try and make things work.

        • Hey Joseph! We are still moving forward with some investigation into tuning the CVT on the Outback XT (and other models). We do not yet have significant updates to share, but progress is still being made.


    • Hey Robert, we do not currently plan to offer a flex fuel solution for the Ascent.


  4. It’s nearly 2022 now, any update for the 2020-2021 outback XT 2.4L CVT issues? An approximate date for an accessport release?
    Thank you, Alex.

  5. Will Cobb be adding support for the 2022 Subaru Ascent? This will help me decide on purchasing a 2021 or 2022. Thanks!

    • We are already hard at work developing support for the 2022 WRX. Once we’re closer to making power and creating calibrations we will definitely share some info!


  6. Please tell me Cobb is at least still working on/planning on releasing a tune for the newer Outback XT/Wilderness! There was a known issue with the CVT controller from Subaru and it has since been corrected. I would imagine this was part of your challenge when tuning. Now that this has been identified – there are a ton of us on the forums eagerly awaiting Cobb support for these cars! SOS!

    • Hey there!

      Tuning for those models is going to require us supporting transmission tuning which is a very large undertaking. I’m not aware of any companies that offer tuning for automotive CVT transmissions at this point, so we would be the first to go down that road. While we have made progress in understanding the relationship between the ECU and TCU, I do not have an ETA for a full tuning solution at this point.


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