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.


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