on an n/a the primary injector section of the wiring harness. does the plug that shares its Y with the coolant temperature plug go to the front(of engine/car) injector, while the single lead goes to the rear?

 

Your description is a little hard to follow but based on what you wrote, yes that sounds right. Depending on which model you have there is 2 or 3 coolant temp sensors on the car. I assume you are talking about the 2 wire sensor on the back of the waterpump just below the thermostat. That plug and the front leading injector would be very close to eachother.

By single lead I assume you mean the single line of loom or heatshrink going to the rear primary which would actually have 2 wires inside it.