Using 90 eprom in 91+ cars or vise-versus.

[Terry Posten]

 

BTW, this is also valid info for the JDM cars e.g. if fitting a 1991 MD165808 ECU into a 1989 VR4 (for instance), the above wire swap is necessary /ubbthreads/images/graemlins/wink.gif.

 

If I may add this link: http://www.dsmtuners.com/forums/showthread.php?t=170393

Shows how to remove/swap the pins in the harness.

 

[jepherz]

Using a '91+ ECU in a '90 is not as simple as just switching the two wires. More info here:
http://www.dsmchips.com/1990ecu.html

 

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.