So, like an idiot I didn't label my fuel injector plugs on the wiring harness when I pulled the harness. I assumed that it would be obvious where each one went based on the length of the harness. Anyways, I was wrong. So, I looked at the wiring diagrams to determine which injector plug was for what cylinder. All well and good, I determined which one was the cold start, and which two were either the 1&3 and which two were either the 2&4.

After looking at the wiring diagram, it appears that the 1&3 cylinders get fuel at the same time and the 2&4 cylinders get fuel at the same time. Am I reading this diagram wrong? It doesn't make sense that two cylinders would get the same amount of fuel at the same time. I would think that they are all separate and would get fuel at different times. But the diagram shows two wires controlling the injectors, each of the two wires control the 1&3 and the 2&4 but split off for another plug so each wire can control 2 injectors.

Anyone with knowledge chime in before I reinstall my wiring harness please. I have the motor back in after rebuilding it and hopefully will have this new motor running soon.

Here is the wiring diagram I am referring to, straight out of the factory FSM:

 

All of the injectors fire at the same time.

 

Is this common on all engines? Also, does the cold start fire at the same time or just for the first few seconds during ignition?

 

The injectors are fed power, 2 at a time, from a "Y" split off ONE power wire that splits into two. The ECU, if you read the diagram, designates each pair into 1 pin each on the ECU, "No.10 and No.20".

The CSI injector is separate, yes, and runs off a Sensor, "The Cold Start Injector Time Switch".... Once that CSI switch reads 98*F or something like that(can't remember, but it's NOT full warm up, lol) ..... it shuts off the CSInjector. That switch is located on the intake, under the throttle body, facing the radiator/grill. It's the sensor on the left, usually brown. The one on the right, usually Green, is the Coolant Temp Sensor, which 'handles' different aspects of the EFI system.

 

Common on earlier EFI engines at least. Cold start injector is run by the cold start injector time switch which is a variable resistor and bi-metal switch in the coolant that turns on after starting (via the ignition switch as I recall) and then as the resistor warms up, it's resistance changes until the CSI is shut off. So the colder it is the longer it stays on.

 

That is the same thing that I was understanding from looking at the wiring diagram. It just seemed odd to me that two cylinders would get gas at the same time through different strokes of the piston.

Thanks for the help guys!!