COBB Brings Speed Density to 2.0L Turbo Subarus


COBB Tuning is proud to announce the immediate availability of our proprietary Speed Density (SD) tuning solution for all currently-supported 2.0L USDM turbocharged Subaru vehicles with manual transmissions! This capability is available as a free update to our AccessTUNER Pro and AccessTUNER Race software and AccessPORT firmware. Our implementation of Speed Density adds our proprietary tuning logic to the factory ECU, enabling it to calculate load, ignition and fueling requirements using the engine’s manifold absolute pressure (MAP) sensor, instead of the factory mass airflow (MAF) sensor. COBB Tuning’s exclusive Realtime tuning capabilities and Hybrid Logic (active switching between MAP and MAF based logic) make this a uniquely powerful and flexible engine management solution. Read on for more details about the work COBB Tuning is doing to make sure the AccessPORT is the most comprehensive OEM ECU tuning solution available for Subaru performance enthusiasts.

Why Speed Density

The most basic function of an engine control unit (ECU) is to measure airflow and its translation to engine load. Precise and consistent load calculations along with feedback from other critical sensors allow the ECU to accurately control ignition timing, variable camshafts, and fuel delivery. The most common way to measure load in modern vehicles is with a MAF sensor. Vehicles with stock engines and mild upgrades can utilize the MAF sensor with excellent overall results. However, in big-build and motorsports applications where power levels are extremely high and intake airflow configurations are less standardized, the use of a MAF sensor can be limiting.

Speed Density tuning using the Subaru factory ECU is a major break-through for high-power Subaru builds. High-power builds using the OEM MAF sensor require very large MAF intake housings to keep the MAF sensor within its usable range, which introduces reduced resolution and unpredictable turbulence that can affect tunability and drivability. Eliminating the need for a very large, high-quality MAF intake housing using Speed Density tuning logic allows for more flexibility when designing a turbo kit and the associated piping and plumbing. Speed Density tuning gives precise control over fueling, timing and other critical tuning components necessary to properly calibrate the vehicle at the very high power levels that today’s big Subaru builds are capable of producing.

Hybrid Logic – Ultimate Flexibility

The Speed Density update for AccessTUNER Pro software offers multiple ECU control modes to give the professional tuner and AccessPORT user a wider choice of engine modifications and tuning options. The software can program the ECU to run in the traditional pure MAF mode, a pure “Speed Density” mode, or a Hybrid Mode which uses both MAF and “Speed Density” with dynamic logic switching between the two.

Tuning Efficiency

COBB’s proprietary Speed Density implementation overcomes many of the limitations and tuning difficulties inherent to the Subaru 2.0L ECU. No longer is there a need to employ hacks to artificially raise the airflow and load limits present in the factory 2.0L ECU. These limits have been internally raised for COBB 2.0L Speed Density, allowing you to simply tune with real-world airflow values (up to 655 g/s) and load values (up to 10.0 g/rev). Additionally, in SD (Speed Density) mode, only the new load limit will come into play, allowing for the accommodation of very high horsepower builds.

We have also made improvements to boost control with 2.0L Speed Density. It is no longer necessary to move away from factory ECU boost control at higher boost levels. New internal changes allow targeting up to 49 psig of boost. We have also incorporated all-new per gear boost targets and wastegate duty compensations, allowing for more precise control of boost in each gear. These new per gear compensations are also compatible with 6-speed transmission swaps, allowing for individual manipulation of boost control in each of the 6 gears.

Tuning aftermarket injectors with COBB 2.0L Speed Density could not be easier. The “Fuel Injector Scale”, “Fuel Injector Latency”, and “Tip-in Enrichment” tables can now be tuned via real-time with COBB 2.0L Speed Density, enabling you to quickly dial in your injector tune. An all-new real-time “Fuel Injector Latency Adder” table allows for tweaking of idle and low load behavior for large aftermarket injectors, resulting in more refined operation during these conditions.

Tuning for aftermarket MAP and IAT sensors is also improved with COBB 2.0L Speed Density. Changes have been made to allow for the full calibration necessary to tune for any Subaru compatible aftermarket MAP and IAT sensors.

Proven Performance

COBB Tuning’s Speed Density for Subarus has already proven capable of tuning big-power Subaru engines. The LIC Motorsports 2004 Subaru STI Time Attack race car claimed the Modified AWD class victory and set a new Modified AWD class record at the Infineon Raceway Global Time Attack 2011 season finale using the AccessPORT and Speed Density tuning. More information about this performance and in-car action can be seen HERE.


Speed Density Availability

This initial release of Speed Density is available for professional tuning shops using AccessTUNER Pro software and for self-tuners using AccessTUNER Race software for the 2002-2005 Subaru WRX.. “Off-The-Shelf” maps will not be made available for Speed Density as custom calibration specific to each vehicle is required.

To have your vehicle tuned using Speed Density logic, simply follow these steps:

  • Contact your preferred Pro TUNER, confirm they have the latest 2.0L Speed Density enabled AccessTUNER Pro software ( and schedule a Speed Density dyno-tune appointment with them
  • OR
  • Update your AccessTUNER Race software to the latest version ( to acquire 2.0L Speed Density functionality.
  • Update your AccessPORT firmware to version (or later) prior to your scheduled tuning appointment. To update your firmware follow this Step-By-Step AccessPORT Firmware Update Tutorial.
  • Download the Subaru 2.0L Speed Density Tuning Guide and read to fully understand this 2.0L Speed Density implementation.

As always, if you have any questions about the AccessPORT and AccessTUNER, or any other COBB Tuning products, please call us at 866-922-3059. Get up-to-date product announcements and COBB Tuning news via our COBB Tuning Mailing List. You can always be a part of the latest conversations with COBB Tuning by tuning in to our our and pages.

10 responses to “COBB Brings Speed Density to 2.0L Turbo Subarus”

  1. Hello, I would to ask you is there a compatibility Speed Density with my impreza WRX Uk edition with Ch.JF1Gf8Br0BG007115 2.0 turbo MY94. What is the price? Special regards

  2. Is it possible to use a Cobb access port to tune a 2003-2004 ej207 version 8 motor with a USDM 2004-2005 STi ecu with AVCS? I was just wondering since Cobb access port only supports USDM subarus wouldn’t it be possible to use the USDM ecu’s on jdm motors and tune them using your product?

    • Pedro,

      The Accessport will work with a USDM STi ECU without any issues, the trick here is in the wiring harness. I do not believe the USDM engine harness is directly compatible with the EJ207. There should be a number of threads on this topic over on as it is becoming a more popular swap.

      [email protected]

  3. Does using Speed Density to tune a 2.0L require a new MAP Sensor? Or can the existing Map Sensor be used?
    I have a EJ20Y Swap in my ’06 Baja 5MT, with the USDM ECU & wiring, and the Tuner is recommending Speed Density bc the car has been having a weird idle & fueling issue.

    • Hi Jason,

      I would recommend it. You can have a functioning tune on the original sensor but for best results, an upgrade is ideal. I would ask your tuner what he recommends specifically.
      [email protected]

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