Currently Viewing:

Gen2 COBB Custom Features for 2015-2019 Subaru WRX


Our Subaru team is thrilled to announce a large update for all USDM 2015-2019 Subaru WRXs.  If you aren’t already sitting, you may want to pull up a chair as this is going to get lengthy.  Nearly three years ago we released the first round of COBB Custom Features for the DIT 2.0L Subaru WRX 6MT.  That release was largely centered around seamlessly adding powerful Flex Fuel capabilities to the 2015-2019 WRX.  As the performance aftermarket for Subaru’s 2015-2019 WRX continues to grow and push the limits of the factory ECU, we saw the need to also expand the capabilities of the Accessport and Subaru Accesstuner Pro HL software.  A new ECU type, dubbed CCF Gen2, is now available for ALL USDM 2015-2019 Subaru WRXs, including those equipped with a CVT transmission.

Vehicles Supported

  • 2015-2019 USDM Subaru WRX 6MT
  • 2015-2019 USDM Subaru WRX CVT

Required Accessport Firmware Version

  • AP3-SUB-004 :

Required Accesstuner Pro HL Version

  • 3.0.0+19115.16455

General Accesstuner Pro HL Improvements

Let’s get started with the easy, but important, notes.  In addition to adding awesome new features to Accesstuner Pro HL for DIT WRXs, we have also made some improvements to the software that everyone benefits from.

Accessport V2 Support Removed

First, we’ve removed V2 Accessport support from Accesstuner Pro HL.  Removing V2 support from the equation makes our development process much quicker when adding new support and features.  Yes, there are still a TON of V2 users out there, and we understand there will be customers that do not wish to upgrade to a V3.  For those situations, a “Golden Build” of V2-compatible Accesstuner Pro HL is hosted at the following link on the COBB Dealer/Protuner website :

Realtime Data Status Added to User Interface

Previously, it was not obvious that the data displayed within tables was a combination of the loaded map file and Realtime ECU data when live-connected to an ECU.  To clarify that, we’ve added an indicator to the header of ATP HL and within the Map Comparison Summary as shown below.

realtime_connect map_compare_plus_rt

Updated Save Prompt Language at ECU Disconnect

In previous versions of software, users would be presented with a save prompt containing unclear messaging regarding changed table data.  That messaging has now been improved to add clarity.

realtime_data_modified mod_rt_disconnect

“Offset Values” Added to Table Editor Tools

Users can now press the “O” key or right-click on table cell(s) to edit by a positive or negative offset.


Percent Difference View added to Map Compare

Further improving the Map Comparison system, our team has added a view that allows for viewing of percentage differences between the active and compared map file.


COBB Custom Features – Gen2

And now, the reason you’re all here.  COBB Custom Features are being expanded in a big way for 2015-2019 Subaru WRXs.  All of the features listed below can now be found within a new ECU type dubbed “COBB v4.0 CCF (Custom Features Gen2)”.  A large change from our previous CCF release for DIT WRXs is the inclusion of support for cars equipped with a CVT transmission.  This ECU type is also based on Subaru’s latest factory programming which includes improvements for longer battery life, and more.

  • Speed Density Tuning
  • Boost Gauge Wrap
  • Boost Extend
  • Boost Smoothing
  • IPW Extend
  • Knock Sum Monitor
  • Load Extend
  • MAF Simple

Speed Density

The COBB Speed Density feature is a powerful yet easy-to-use solution that integrates Speed Density tuning into the Subaru engine control unit (ECU) and can be used to entirely replace or work in conjunction with the existing factory mass airflow (MAF) sensor. It is highly customizable and features such as real-time tuning aid in a speedy and efficient tuning process.  Utilize the Speed Density tuning strategy on cars producing airflow that exceeds what is measurable by the factory Mass Airflow sensor or in situations where airflow calculations are inconsistent due to mechanical configuration.

  • Calculate airflow/load from manifold pressure, manifold temp and other inputs.
  • Uses the ideal gas law with true volumetric efficiency (VE) tuning.
  • Dynamically switch between MAF and SD with the Hybrid feature.
  • Supports up to 100 psi manifold absolute pressure (aftermarket MAP sensor & calibration required).
  • Real-time tuning of VE and select other SD tables.
  • Uses unique tune-able manifold pressure smoothing for SD.
  • TGV closed and open VE tables help to better account for VE changes due to AVCS table switching.
  • Special post-start VE tables help to better account for VE changes due to inactive AVCS for a period after start.
  • VE adder allows for VE compensation in stratified fuel mode.

Load Extend

The factory load limit of 3.3 g/rev has been increased to 10.2 g/rev to allow for tuning of cars making up to ~1000 ft/lbs without having to skew load values.

  • Tables with load extend will show the load axis as “Calculated Load Extended”.
  • For your convenience, all the load extend tables are duplicated in the “Cobb Custom Features” → “Load Extend Tables” group.
  • Introduces new “Calculated Load Extended” monitor to Accesstuner and Accessport.

Boost Extend

  • Raises boost target, boost limit, and boost monitoring hard-coded factory limits from 24 psi (relative at sea level) to about 87 psi (relative at sea level).
  • Also raises the manifold pressure and boost targets limits by the same amount on 20 key tables and boost error to a -50 psi to 50 psi range on an additional 5 tables.
  • Tables with boost extend will add “Extended” to the end of the axis unit name (ex. “Boost Targets Extended”). For your convenience, all the boost extend tables are duplicated in the “Cobb Custom Features” → “Boost Extend Tables” group.
  • This feature requires an aftermarket manifold pressure sensor with the appropriate range and map calibration in order to take advantage of the higher limits.

Injector Pulsewidth Extend

  • Increases the pre-fuel pressure compensation IPW limit to more than 10 times the old factory hard-coded limit, making it unlikely to ever be exceeded.
  • Old factory limit could be hit at higher loads, causing a lean condition where IPW goes static at about 7.x ms at WOT (post-fuel pressure compensation).
  • This feature is completely transparent – no tuning changes required to make use of the new higher limit.

MAF Simple

  • The MAF Simple feature allows you to transition from the highly complex factory airflow model to a simple MAF calibration based airflow calculation at higher load/boost.
  • This facilitates a more accurate airflow calculation for cars that exceed or are close to exceeding the old load and boost limits.
  • Tuneable load and ramping thresholds allow the system to be customized as needed.

Boost Gauge Wrap

  • Allows for monitoring boost past the OEM limit of 24 psi on Subaru’s factory boost gauge screen.
  • Gauge will wrap-around when 24 psi is exceeded, allowing you to effectively read up to 44 psi of boost (with default set-up – potentially higher with additional tuning changes).
  • Default set-up uses a 20 psi base in Wrap mode making it easy to calculate the new boost level in your head – 10 psi on gauge when wrapped is 30 psi actual (20 + 10 = 30).
  • Can be customized with a different wrap threshold and/or different base offset. Or can be disabled if not desired (feature is enabled by default).
  • NOTE: The boost wrap feature cannot represent boost higher than the MAP sensor installed to the car is capable of reading. A correct barometric pressure reading is also required for the feature to work properly.

Boost Smoothing

  • Manifold pressure can be smoothed by separate factors for boost control and for the COBB SD airflow calculation.
  • This allows for custom changes to separately filter out “noise” in the pressure reading used in boost control and SD without impacting other ECU functions that use manifold pressure.

Knock Sum Monitor

  • A new custom knock sum monitor has been added that increments when the factory knock signal perceives a knock event.
  • This knock signal is the same signal used for all knock responses by the ECU (feedback knock correction, fine knock learning, and the DAM).

Fuel Economy Gauge Correction

  • Fuel economy gauge correction feature allows correction factors to be tuned to improve accuracy of factory mpg gauge.
  • Also included in the Flex Fuel feature, allowing for separate tuning and blending of gauge correction across low to high ethanol contents.

Intake Temp Override

  • Intake temp override feature (when enabled) allows using manifold temp in place of pre-turbo (MAF) intake temperature for all applicable tables and other functions in the ECU.
  • The actual pre-turbo (MAF) intake temp can still be logged even when the feature is active.
  • This feature was originally introduced only in the 18-19 WRX CCF Gen1 ECU type but is now available for all DIT WRX vehicles in the new CCF Gen2 ECU type.

Gen1 CCF Improvements

In addition to the new features, we have also made improvements to features pulled forward from the original CCF ECU type.

  • TGV Duplication Mode function (previously found only in EJ 2.5L CCF) to the Custom Sensor feature.
  • Ethanol Sensor Concentration Override Always table allows the Flex Fuel system to operate with fixed ethanol value even when ethanol sensor input mode is set to disabled.
  • Adds the Ignition Timing Compensation (Intake Temp) table to the Flex Fuel assortment for the 15-17 WRX to allow for separate tuning and blending of gauge correction across low to high ethanol contents. This table was previously only available in the 18-19 WRX Flex Fuel assortment.
  • Note: these improvements are only available in the Gen2 ECU type (not Gen1)

**More information regarding these features can be found in the following document : Subaru DIT V4.0 CCF (Gen2) Additions


Expanded Realtime Table Support

The following tables are now available to be added to the Realtime Tuning and Map switching assortment.

  • Boost Limits Base
  • Closed Loop Fueling Target Base (Main) D (Higher Load)
  • Fuel Pressure Target Main
  • MAF Simple Mode Airflow Corrected Smoothing Factor
  • Manifold Pressure Smoothing Factor (Boost Control)
  • Manifold Pressure Smoothing Factor (SD)
  • SD Airflow Compensation (Intake Temp)
  • SD Airflow Corrected Smoothing Factor
  • SD Mode (0 = MAF, 1 = SD, 2 = HYBRID)
  • SD Volumetric Efficiency A

The below tables have been removed in order to make space for the above.


  • Dynamic Advance Base (TGVs Open)
  • Primary Open Loop Fueling Base (TGVs Open) Main


Additional Factory Tables/Monitors

The following sets of Subaru OE tables and monitors have been added to the Accesstuner Pro HL software and Accessport firmware.

Added Tables

  • Target Throttle Limit (Max) Rev/Boost Limits Mode On (Throttle Cut Default – Low)
  • Target Throttle Limit (Max) Rev/Boost Limits Mode On (Throttle Cut High)
  • Target Throttle Limit (Max) Rev/Boost Limits Mode On (Throttle Cut Moderate)

Added Monitors

  • A/C Compressor Switch
  • Closed Loop Delay Count
  • CPC Purge Fuel Trim
  • CPC Purge Valve Duty
  • Engine Start {Mode}
  • Manifold Abs. Pressure Sensor Voltage
  • Mass Airflow {Table}
  • Post-Start AVCS Disabled Map Ratio
  • Radiator Fan Relay #1 Switch
  • Radiator Fan Relay #2 Switch

Miscellaneous Bug Fix

A bug where the “Intake Temperature Pre-Turbo” monitor would occasionally display a value of -58F for a brief period post-start has been addressed.  This is a monitor-only fix.