Planning for more inputs/outputs

Completed the efi wiring fundamentals and am very happy with what I learned.

I do have a couple of questions though.

What is the best way to plan for more sensors or upgrades after the initial harness is made?

Do you put all of the extra inputs into one connector and the outputs into another connector?

Also would need to plan for more 5v and sensor grounds.

Its pretty common to leave either a "Spares" connector with ground, power and signals -- sometimes this is just in an intermediate bulkhead connector. If it's easy enough to add pins to the ECU connector later, i.e. you don't have a boot over the back of the connector, then you can just add terminals when it comes time to expand, and splice into the necessary powers and grounds.

David is on point here. I'll also almost always put a 'spare' connector in the harness, usually close to the ECU that has unused inputs and outputs, and usually a 5v sensor power and sensor ground too. I will almost always put a spare CAN connector in there as well, which has +12V main power, power ground, CANH and CANl too, makes it easy to temporarily pop in a device that needs access to the CANBus.

Thanks guys. Appreciate the feedback, just want to make sure I’m doing things correctly

Further to what Zac said, i usually split my spare connectors. 1 in the engine bay if you need additional sensors later, and one in the cabin near the ECU. And yes, adding an extra CAN slot is a great idea.