Injector wiring-factory rework

Hey there! I’m currently working on a 2002 SVT focus (ST170) and am looking to re-do the factory wiring to cut down on clutter and learn to be less scared of wiring. I’ve got down to the level on it, most of the wiring for the body and engine has been removed and I’ve been using ropes to plan the layout. I’ve just got a question regarding injectors. In the lesson, it was mentioned that injectors are low-side switched, and as such +12V can be run from one main wire and split out to each injector. Their ground paths can then be run back to the PCM for control. Now, this is great, and I’d love to do it on my car, but according to both wiring diagrams and the wiring as it sat from factory, each injector has its own dedicated +12V and ground wire. I’m curious if there are any established ways to just use a single wire for +12V and to branch it out to each injector in a system like this. I know it’s a bit of an odd ask, but as it stands now, the factory engine harness is connected to the PCM by two chunky connectors (one 16-way and one 6-way) in the exact same location, and cutting down the number of wires going through these connectors may enable me to just use a single 20-way connector. Which, by the way, I’ve only been able to find 2-row 20-way connectors for K-swaps, so if anyone is aware of a robust and sealable alternative, I’d love to know about it. Thanks folks!

Sam,

That's not an odd ask at all.

If you've confirmed your vehicle operates in the typical fashion you've mentioned, with pulsed ground injector control, then you can usually split a single 12V supply to all the injectors. As long as the single primary wire can support the total draw of the system, the current handling isn't a concern.

One caveat is I don't know if that ECU performs error checking that might somehow pick up on this change, so I'm just throwing that out there as a possibility.

I'm not a wiring expert, but I've seen what you're wanting accomplished in one of 2 ways.

Both involve splices executed as shown here in the course:

https://www.hpacademy.com/dashboard/courses/practical-harness-construction-club-level/practical-wiring-harness-construction-skills-splicing-supply-ground-wiring/

In terms of layout, the two ways I've seen it done are a single 1 to many splice like in the video, or the other route is the primary wire is treated like the trunk of a tree and for each injector there's an inline splice allowing a small branch off the trunk to the injector, and ultimately the trunk wire connects to the final injector in the line.