Does the polarity of the 2 wires (1 with the resistor) coming off the injector to the wiring harness matter? If so, what color is which?

 

It does not really matter. I prefer to put them on the ECU wires which are the green ones. This is because I mount them in the cabin next to the PFC to prevent them from seeing too much heat, vibration etc.

 

Thanks for the info. How much ohms do you use. I have 3 ohm ones, I assume thats fine.

 

3 ohm is fine. From the most recent information found it seems 1 ohm is fine.

 

In a DC series circuit with non-polar devices, it does not make any differance how they are hooked up.

Here is a weird fact: Mazda uses some different size wires on some of their connenctors.
Look at the injector connectors. Thus the thinner one would increase resistance for that leg of the circuit and would be the section to burn out first if it had a run-a-way short.