ECU wiring, relays etc.

[Jonny Rochester]

I have wired up a few computers and can manage this and get it all the work. But I am just fishing for ideas to make it work 100% and be nice and neat.

I notice on a few factory diagrams, the injectors are just powered off the ignition switch?
Main EFI relay powers everything else, including the fuel pump.
The fuel pump relay (circuit opening relay) is powered by the main EFI relay.

For a aftermarket ECU, you may have a fuse near the battery, then a relay powering everything else. (Or any positive wire you find fishing under the dash). Injectors could be powered by anything (not sure how much current the draw or if it matters). And often you have a seperate relay for the fuel pump, triggered by the ECU.

Would it be of any benifit to have a seperate power wire and relay for:
ECU
Injectors
Fuel pump
coils

With this setup it would be easy to have a switch on each system for a home made imobolizer.

What is the most common setup people use?

[The Witzl]

There is no reason why you cant do that, but for the most part it will just add excessive relays.

Personally i can only see the need for one, maybe two power relays other than the fuel pump relay.