Map Notes for Ascent

Supported Vehicles:

  • Model year 2019-2021 Ascent

*To confirm your model year, you can refer to the tenth value in the VIN number on the vehicle. For model year 2001-2009, the 10th value in the VIN will be the last digit of the model year. For model year 2010-2019, the 10th value in the VIN will be A-K, starting with 2010, ending with 2019.


Current Map Revision:

North American 2019-2021 Ascent

performance maps

North American 2019-2021 Ascent

non performance maps

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

Accessport Firmware: 

  • AP3-SUB-005: 1.7.3.0-19161 or greater






Fuel Requirements:

Each map lists the minimum required octane. A higher octane fuel can be used safely on a map designed for lower octane. DO NOT use maps designed for higher octane with lower octane fuels. Top Tier gasoline should be used where available.

  • Maps designated with "93" are for use with 93 and 94 octane/98 RON fuel or better with ethanol content between 10-20%.
  • Maps designated with "87+" are for use with 87octane/91 RON fuel or better and work well with 87-89, 91 (ACN and otherwise), 92-94 octane fuels with ethanol content between 0-20%.

If you'd like to keep things simple and aren't interested in monitoring and switching maps to maximize power for premium fuel, the 87+ performance map allows you to run any quality gas in the 87-94 octane range, which is available at almost all public gas stations in North America.

If significant knock (more negative than -2.8 degrees) is present when using 93 octane calibrations on 93 octane fuel, switch to a map that is intended for a lower octane fuel to better suit your fuel quality. The octane label on the gas pump doesn't tell the whole story. Despite the label, a 91 or 87 octane map may more accurately represent the "93" octane fuel in your tank. Monitoring your vehicle via the Accessport and selecting the OTS calibration that best suits your current fuel quality allows you help your engine run safely, while retaining as much extra performance as possible.

A common example is "winter gas" sold in the northern USA and eastern Canada. In the summer time, the 93-94 octane fuel in those areas is generally in the ballpark of high quality southern USA fuel. However, when it's not summer time, "winter blend" fuels are often sold, without notice of the change being made. Winter gas formulations are designed to aid in cold engine startup and to reduce cold engine emissions. In order to achieve those goals, the formulation is changed and volatility of the fuel is increased on purpose, making the fuel more likely to cause knock. "Winter blend" fuels sold as 93-94 octane in those areas are often on par with 91, or even ACN91 summer time fuel in terms of knock resistance. For that reason, our 91 or ACN91 fuel maps better match winter blend 93-94 octane fuel quality, and no single map (OTS or custom) can fully optimize for the range of fuel quality in that area. 





Please refer to your vehicle’s tow rating/guidelines when using COBB OTS Maps. Vehicles may see higher than normal temperatures while towing using either factory OR performance tunes. We suggest keeping an eye on CVT temperature while towing and avoiding situations where the temperature rises above 240 F.






 




Peak Gains

Maximum Gains                 

Stage1 93

+11% HP,  +16% TQ

+22% HP,  +22% TQ



Stage1 93

  • Intake Requirements: Stock airbox and stock air filter
  • Exhaust Requirements: Stock
    • Increased boost targets and limits, adjusted compensations for intake air temperature and barometric pressure, wastegate position and turbo dynamics adjustments.
    • Air metering, fuel delivery, and ignition timing optimizations for fuel quality, air temperatures, barometric pressure.
    • Knock system adjustment to allow knock response, but prevent false learning, only in low load areas i.e. idle, cruising. Knock detection load limit increased to allow knock detection at increased boost levels.


  • Peak gains are measured as the difference between the highest points of the two plots.
  • Maximum gains are measured as the largest gain at any single point between the two plots.

Results will vary based on atmospheric conditions, vehicle condition, dyno used, etc.

Calibrations are only designed to work with the above parts and the addition of any other hardware may make the vehicle perform poorly. 

**Subaru advertises the Ascent CVT transmission as a "high torque" unit, but some owners of stock vehicles are reporting transmission failures on the stock tune. Tuning your vehicle voids your powertrain warranty. Tuning products are to be used at your own risk, so consider carefully before proceeding.**





Peak Gains

Maximum Gains                 

Stage1 87+

+8% HP,  +4% TQ

+18% HP,  +18% TQ


Stage1 87

  • Intake Requirements: Stock airbox and stock air filter
  • Exhaust Requirements: Stock
    • Increased boost targets and limits, adjusted compensations for intake air temperature and barometric pressure, wastegate position and turbo dynamics adjustments.
    • Air metering, fuel delivery, and ignition timing optimizations for fuel quality, air temperatures, barometric pressure.
    • Knock system adjustment to allow knock response, but prevent false learning, only in low load areas i.e. idle, cruising. Knock detection load limit increased to allow knock detection at increased boost levels.


  • Peak gains are measured as the difference between the highest points of the two plots.
  • Maximum gains are measured as the largest gain at any single point between the two plots.

Results will vary based on atmospheric conditions, vehicle condition, dyno used, etc.

Calibrations are only designed to work with the above parts and the addition of any other hardware may make the vehicle perform poorly. 

**Subaru advertises the Ascent CVT transmission as a "high torque" unit, but some owners of stock vehicles are reporting transmission failures on the stock tune. Tuning your vehicle voids your powertrain warranty. Tuning products are to be used at your own risk, so consider carefully before proceeding.**




Non- Performance Maps






  • Vehicle Anti-Theft Mode
    • Will not allow vehicle to start
  • Economy Mode
    • Max boost target:  Typically around 6psi
    • Max engine speed reduction via max throttle reduction
  • Valet Mode
    • Max boost target: Typically around 6psi
    • Max engine speed reduction via max throttle reduction
    • Speed limiter, 2 stage. Throttle reduction past 60 MPH, fuel cut at 70 MPH.






Monitoring Boost Levels: 

The best way to determine if you are hitting target boost is to watch the TD Boost Error parameter. This parameter is your target boost (including altitude and temperature compensations) minus your actual boost (negative values mean you are over the target by the amount while positive values mean you are under). The monitored value will bounce around, but ideally you want this value to average between -1.0 to 1.0 at wide open throttle (WOT).  Keep in mind however that due to turbo size and efficiency the amount of boost pressure will gradually decerase as you approach redline.  Overboosting has been reduced from the stock tune, but may still occur to some extent during abrupt throttle transitions and shifts. Throttle closure and overboost fuel cut measures are in place IF boost starts approaching safe limits.


High Altitude: 

A quick note for those of you that live at higher altitudes: it is common for turbocharged cars at higher altitudes to run less boost pressure due to lower air pressure and air density. Your turbocharger has to work harder to compress a less dense air mass compared to the same turbocharger at sea level. This must be factored in when determining if your turbocharger is running the proper amount of boost pressure and not being pushed beyond its efficiency range. 

There are barometric compensations within the factory ECU that adjust boost targets as you climb in altitude in an effort to keep the turbocharger in its optimal range. The COBB performance maps have tuned these compensations and therefore, it is perfectly normal for boost target to be change as barometric pressure changes.






Revision Notes: 

1.01 Support Released