Support for JDM Forester STI EJ255, Legacy 2.0GT EJ20X EJ20Y

We are excited to announce that we have added software support for some popular JDM Subaru models. You can now tune your ECU with our advanced software and get the best performance out of your engine. Base maps are also available to help get you tuning quickly.


JDM 2003 – 2006 Forester STI SG9
Base Map Gains: +50 whp, +46 ft-lbs

The JDM Subaru Forester STI is a rare and powerful version of the popular SUV, with a turbocharged 2.5-liter EJ255 engine that produces 261 bhp and 279 lb-ft. Our base map gets you more performance than a much newer EJ257 at 310 bhp and 325 ft-lbs.


JDM 2003- 2006 Legacy B4 GT and spec.B, BP5/BL5
Base Map Gains: +10whp, +53 ft-lbs

The 4th generation JDM Subaru Legacy BP5 or BL5 with EJ20X or EJ20Y received twin-scroll turbos and dual AVCS for better drivability and low-end torque but the stock tune is so tame that you can barely tell! This can all be fixed with our software and tuning. Greatly improved throttle response and low to mid-range torque makes the car much easier and enjoyable to drive. The fuel economy gets better too. There are really no negatives to tuning these engines.

These cars have been available in the Beta version for quite some time now, so you can rest assured they have been well tested.

We are always working to expand our software support for more Subaru models and engines. We can add almost every phase-2 EJ engine and some FA and FB engines too.

Stay tuned for more updates and happy tuning!


Full List of Cars Added


BL5A 2003 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BL5B 2004 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BL5C 2005 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BL5D 2006 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BP5A 2003 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BP5B 2004 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BP5C 2005 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y
BP5D 2006 Subaru Legacy B4 2.0GT and spec.B EJ20X/EJ20Y

SG9C 2003 Subaru Forester STI EJ255
SG9D 2004 Subaru Forester STI EJ255
SG9E 2005 Subaru Forester STI EJ255
SG9F 2006 Subaru Forester STI EJ255

Special editions of all the above with the same engine code will also be compatible.

Bluetooth Tuners Back in Stock

Finally, we have Bluetooth Tuners back in stock!

Due to chip shortages, we had to redesign the circuit to use alternative chips that could be procured in a reasonable time. Antenna design was also optimized, resulting in a 60% increase in signal range. Combined with new firmware, the total signal range improved by a whopping +200%.

Also, material and production costs have gone up considerably so we are going to have our first price increase in our 7 years of operation. You can still get old pricing at our web store until the end of March 12, 2023. Get yours now!

Next up, our main focus will be on major software improvements and a new mobile app that supports logging and reflashing.

JDM EJ205 24 PSI on Stock 2.5RS ECU

MY2000 Impreza EJ251 ECU Running a Turbocharged EJ205

The Subaru Impreza 2.5RS sedan and coupe have been a popular platform for turbo swaps for a while now. Typically the donor turbo engine was not compatible with the factory EJ251 ECU and required a complicated wiring harness merge to get the car running on a swapped-in turbo ECU. Here you can see how it can be done without the wiring hassle by keeping the EJ251 ECU and using our projectLAMBDA Tuner to get it to play nice with the turbo engine. With the engine harness connectors being nearly the same, the swap becomes almost a plug and play affair.

For this build, an EJ205 from a JDM Forester SF5 was swapped in to replace the original EJ251. Other suitable candidates are the EJ207 and EJ205 from the Impreza GC8 and GF8 WRX/STI. A lot of the sensors and wiring are shared between these 2 engines despite the fact that one is turbocharged and the other is not. Both come with a 32-bit ECU although the JDM runs on a mass airflow sensor, has different harness connectors and does not support OBD2 protocol. The USDM NA ECU uses a speed density fuel calculation instead of MAF and also has a Bosch LSU 4.2 wideband front O2 (lambda) sensor from the factory so that needs to be taken into account when doing the swap. The USDM ECU also does not have boost control but we are going to change that in the future. For now a manual boost controller was installed to keep the turbo under control.

The original EJ251 intake manifold has a Bosch 1.0 bar TMAP installed in the plenum to measure manifold pressure and air temperature. Since the EJ205 does not have any provision for this, a GM intake air temperature sensor was installed to support the ECU’s speed-density fueling. A 3.0 bar MAP sensor measures boost off one of the intake manifold vacuum ports. Another cleaner option would be to modify the manifold to fit a Bosch Motorsport 3.0 bar TMAP. This gives minimal measurement delay on the MAP signal versus a remotely mounted MAP sensor.

The owner stepped up from the original TD04HL to a modified VF39, then finally an FP Blue along with supporting mods to reach his power goals. In its current form, the engine is tuned for up to 24 psi of boost on 93 octane pump gas, but 22 psi seemed to be the sweet spot for power and torque. This could be a limitation of the unmodified EJ205 heads and cams. Not bad at all considering the JDM EJ205 tune has a boost target of only 10.6 psi. The end result is a cool-looking daily driver that can back up its looks with performance.

Build Info

  • MY2000 Impreza 2.5RS sedan chassis
  • JDM EJ205, stock block and heads, 9.0:1 CR
  • FP Blue Turbo with EWG, 1.0 bar wastegate spring
  • DW1000 Injectors
  • VA STI top mount intercooler
  • Header, downpipe, exhaust

New Launch Mode, Pops and Bangs in Version 1.4.1

Version 1.4.1 of projectLAMBDA Tuner adds settings for Launch Mode and Pops and Bangs. These much requested features can easily added to any tuned ECU supported by projectLAMBDA.

DISCLAIMER: These features have the potential to cause engine damage, increase wear on engine components, and make your neighbours hate you. Use them responsibly.

Launch Mode

Launch Mode uses a simple 2-step rev limiter instead of the regular rev limiter when vehicle speed (wheel speed) is below a configured threshold. Turbo ECUs also have the ability to retard spark timing to build boost and shoot flames while on the limiter.

  • Launch Mode – Enable: Set to 1 to enable Launch Mode function in the ECU.
  • Launch Mode – Maximum Vehicle Speed: Launch Mode rev limiter is used instead of the regular limiter when vehicle speed is below this threshold.
  • Launch Mode – Rev Limiter: Works the same as the regular rev limiter but used only when Launch Mode is enabled.
  • Rev Limiter – Spark Retard (Turbo ECUs only): Retards spark timing when either the Launch Mode or regular rev limiter is activated.

Pops and Bangs

To get some noise during deceleration, you will need to edit some Deceleration Fuel Cut and Spark Timing maps. Normally during decel, fuel is turned off so no combustion occurs. You will need to increase the delay time before fuel is cut off. Threshold settings can be used to limit when this occurs to above a specific RPM and vehicle speed. The car needs to be in gear and moving for this to work.

NOTE: Some ECUs may have more settings than the ones listed here.

  • Deceleration Fuel Cut – Enable Delay: Increase this to get fuel to stay on during decel.
  • Closed Throttle Spark: This is the spark advance used when throttle is closed. Reducing spark timing at higher RPM will cause more of the combustion to occur in the exhaust rather than in the cylinder, creating more noise and possibly flames.
  • Fuel – Load Compensation: Reducing or increasing fuel at low load regions where deceleration occurs can change the sound of the pops. This can be tuned along with spark timing to get the sound you want. The exact settings will depend on your mods and engine condition. Too much or too little won’t combust and will have little effect.
  • Spark – Minimum: Some ECUs limit the minimum spark timing. If you need more spark retard, then check this map.

Configuring the JDM Legacy EJ206/EJ208 ECU for single turbo operation

Previously, swapping to a single turbo in the JDM Legacy meant also swapping to a single turbo-capable ECU with the same connector type. This ECU swap required downgrading to a wasted spark coil pack, removing the fuel pump control module and associated wiring changes.

Now with version of projectLAMBDA Tuner all that hassle is no longer necessary. You can configure your stock TT ECU for single turbo operation without swapping the ECU or modifying wiring. The basic concept is to reflash the ECU to a single turbo firmware with some modifications specific to the Legacy engine. This allows removal of all twin-turbo specific sensors and actuators without triggering a CEL. An added benefit is the boost control has an additional map ‘Wastegate Duty Cycle – Base’ which can be tuned for better boost response instead of waiting for closed loop control of boost to kick in when throttle is increased.


  1. Create a new single turbo calibration. File->New, select 2000 JDM Forester AE831.
  2. Enable Fuel Pump Controller output. Set ‘Configuration->Fuel Pump Controller – Enable’* to ‘1’.
  3. Enable Coil on Plug ignition output. Set ‘Configuration->Coil On Plug – Enable’* to ‘1’.
  4. Copy ignition coil dwell maps:
    Rev A and B coils (black): Copy over ‘Spark Timing->Ignition Coil Dwell Base’ and ‘Spark Timing->Ignition Coil Dwell – RPM Compensation’ maps
    Rev C coils (grey): See maps at end of page.
  5. OPTION: The primary wastegate solenoid is on opposite side of the engine bay from the single turbo.  The secondary wastegate solenoid connector can be used instead by repinning the ECU versus splicing and extending the wires from the left hand side of the engine bay or having very long boost control hoses.
  6. Copy over any other maps you may want to keep the same such as Rev Limit, Boost Limit, Fuel, Spark Timing, Knock Control.
  7. Reflash the new tune and start tuning!

*There are separate settings for MT and AT transmissions. It won’t hurt to set up both.


projectLAMBDA Tuner 1.2.5 Released

Version 1.2.5 is now available for DOWNLOAD.

New Features

  • Added trouble code reader
  • Added more knock control settings
  • JDM ECUs: Added coil dwell settings
  • AD983, AE800, AE801, AE802, AE860, AF040, AF331, AH960: Now supported

Bug Fixes

  • Fixed an issue when initiating the BlueSSM connection.


If you have a JECS ECU that is not supported yet, please let us know using the Vehicle Request Form. Your ECU can usually be added to the software within a few days.

projectLAMBDA Tuner 1.2.2 Released

Version 1.2.2 is now available for DOWNLOAD.

New Features

  • License updating now uses copy/paste text instead of license files.
  • AF041, AE831: Boost maps added to live tuning
  • AG292 (EJ206 Rev C): Now supported

Bug Fixes

  • JDM ECUs: MAF bias now works properly when MAF limit is changed. Log parameters updated.


If you have a JECS ECU that is not supported yet, please let us know using the Vehicle Request Form. Your ECU can usually be added to the software within a few days.

projectLAMBDA Tuner 1.2.1 Released

Version 1.2.1 is now available for DOWNLOAD.

New Features

  • ECU reset command
  • Read ECU RAM for troubleshooting and debugging
  • AG302: Boost maps added to live tuning

Bug Fixes

  • AD984: Can now be flashed safely
  • AF041, AE831: Can now be licensed and reflashed


If you have a JECS ECU that is not supported yet, please let us know using the Vehicle Request Form. Your ECU can usually be added to the software within a few days.

JDM Legacy BE/BH base maps now available!

Legacy EJ206/EJ208 (Rev A,B,C,D) Base Map ECU Reflash: 400 CAD

  • Tunes your stock ECU to eliminate knocking caused by aggressive JDM spark timing
    • Spark timing reduced to safe level for Canadian pump gas
    • Revised boost control for higher boost and quicker turbo spool
    • Reduced torque dip during primary to secondary turbo switchover
    • 180 kph speed limiter deleted
    • Radiator fans turn on earlier to keep engine cooler
    • MAF sensor range increased 35%
    • ECU will get a Project Lambda Tuning license which allows reflash using BlueSSM (Rev A,B,C only)
  • Maps available for 91 and 94 octane
  • Car will be data-logged to verify engine is running safely with reflash

Text David from Drivehard Performance @ 604-711-4564 to book an appointment or call 604-270-2494 for further inquiries.

Pro Tuning Service

  • ECU will be custom tuned for your modifications and fuel octane
  • Wideband Air/Fuel Sensor will be temporarily installed if you do not already have one
  • Performance gains are measured with road dyno software; dyno tuning available at additional cost
  • Please make sure your vehicle is in good condition or let us know of any issues that should be addressed before proceeding with tuning
  • Typically 4 – 6 hours labour @ 120$/h

Text David from Drivehard Performance @ 604-711-4564 to book an appointment or call 604-270-2494 for further inquiries.



Example results for stock Legacy B4 RSK 5MT EJ208 (Rev C) with hose 10 modification.

94 octane whp wtq (lbf-ft)
Stock (5C day) 187 172
Stock (-6C day) 209 198
Base Map 217 206
Pro Tune 228 212


91 octane whp wtq (lbf-ft)
Stock N/A* N/A*
Base Map 206 194
Pro Tune 218 200

Power measurements use SAE correction factor (25 C, 0.99 bar)
*Stock measurement on 91 octane could not be completed safely due to excessive knocking

Boost curve for Rev C. Rev B primary boost target is 12.5 psi, secondary target is the same as Rev C.

projectLAMBDA Tuner 1.2 Released – JDM/EDM/ADM ECU Support!

Version 1.2 is now available for DOWNLOAD.

New Features

  • JDM/EDM/ADM ECUs can now be read and reflashed
  • Map editing for the following vehicles:
    • SF Forester EJ205
    • GC/GF Impreza STI EJ207
    • BE/BH Legacy B4 RSK EJ208
  • Following vehicles will be added for next release:
    • GC/GF Impreza 2000 EJ205
    • GC Impreza P1 EJ207

If you have a JECS ECU that is not supported yet, please let us know using the Vehicle Request Form. Your ECU can usually be added to the software within a few days.