1G 90 eprom ecu into 91-94 car

[1991GSXAWD]

Eprom# 742 is there anything i should be aware of? should i skip this ecu and go for the 91-94 eprom ecu?, my car is a 91 Eclipse GSX

 

[Old Mitsu Tech]

There's 2 wires you have to swap to run the 90 in a 91 or a 91 in a 90. If you cannot find the schematic for the switch let me know and I'll try to find it for you.

Or, like you said, you can purchase a 91 pcm and not have to do anything. Except maybe socket it.

Good Luck

 

[1991GSXAWD]

beside the 2 wires, is the tach going to work ok? thanks for your help

 

[EclipZ]

with my experience, the tach will jump down to 0rpm when you floor it. but i did the oposite, put a 91 ecu in my 90 car. i had to rewire the coil pack, transistor and replace both units with 91 equipment. i also had to change out the tachometer in the guage cluster which was easy. im not sure if you would have to switch out to 90 parts or not.

the only thing switching the 2 wires on the ECU are for is the mass air flow sensor.

 

[1991GSXAWD]

maybe i should just stick to the 91-94 to avoid the tachometer issues

 

[oldman]

Allow me to clarify.

1. 90' ECU in a 91'+ car only requires swapping of pin 6 and pin 14.

2. The tach problem mentioned is only associated with putting a 91'+ ECU in a 90' car, the swap is a little more involved.

 

[90laserRSfwd]

Allow me to clarify.

1. 90' ECU in a 91'+ car only requires swapping of pin 6 and pin 14.

2. The tach problem mentioned is only associated with putting a 91'+ ECU in a 90' car, the swap is a little more involved.

Just proved this statement to myself today!