Description
This is the latest Mitsubishi Factory ROM which is calibrated for the 1999 Specification ECU along with the ECUFlash XML file.
Yes there is a difference!
The 1999 Specification ECU has a different O2 calibration which can “see” down to about 200mv vs. the 1998 Specification ECU which can only “see” down to 300mv. Although this is a small change, the code is designed for this. Running a 1999 ROM (or Greg’s Chrome) on a 1998 ECU or the competitor’s ECUs will filter out the lower 300mv of the O2 rendering the ECU effectively “blind” from heavy lean conditions.
The 1999 Specification ECU also has different throttle circuits which the 1999 ROM is designed to take advantage of in order to remove the dreaded lean tip in throttle or acceleration stumble conditions. This was a known problem which is why the Mitsubishi Engineers released the latest ROM for the 1999 3000GT. Running a 1999 ROM (or Greg’s Chrome) on a 1998 ECU or the competitor’s ECU will not take full advantage of this and you may occasionally experience a part throttle stumble or lean tip in condition. This is not just a code issue and can only be fixed by running the proper ROM with the proper ECU.
All of the Official Clone ECUs are re-manufactured to the 1999 Specification.
