Ok guys I checked out the voltage of the rear secondary and primary injectors. It came out to be 4 volts. I'm not sure why it reads that low. You guys think my ecu is fired? I found out that the car had a wire that was melted; the wire comes from the right side(passengers side) of the fire wall. Its from the motor to the ecu. Please help! I'm new to mazdas. P.s. I have a s4 fc mazda 1987 turbo type two. How do you check if your ecu works?

 

Measurng the voltage with a Voltmeter (on dc or ac setting btw?) is not going to tell you much because it will be a square wave that is driving the injector.

Perhaps you can compare with the front rotor voltage using that same method.

What is it that the car is doing wrong? Is it just that there is a melted wire?
If it was a S5 I'd say check for error codes bit I'm not sure if S4 does that....