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Using 90 eprom in 91+ cars or vise-versus. | Galant VR-4 > How To and Info Archive | GalantVR-4.org Mitsubishi Galant VR4 Forum
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It is also worth mentioning that there is only ONE known issue with using the 1990-style ECU in your 1991+ DSM: the tach pulses are inverted, so the ECU never sees misfires, so it will never throw a Code 44 if you have a bad transistor or coilpack. Otherwise, it runs perfect by just swapping pins 6 and 14, as shown above.