So I'm trying to build my own megasquirt harness I just cant figure out where the rest of these wires go I have the 3.57v megasquirt and Im trying to install it in 90 1.6. I bought the wire loom off of diyautotune. Im not sure where exactly to run the fuel pump wire, IAC 1b, all the can wires, pwm idle wire, one random black and white wire, and finally the shielded tac wire. Any help would be greatly appreciated.

 

There are Mazda OEM FSM's as stickies. They have detailed wiring diagrams including the pinout of the OEM ECU. That's where you should go.

 

FSM is your friend, or any 90 specific wiring diagram. BTW your car doesn't have a CAN, and is a PWM IAC, so you won't use all the IAC wires either.