Ignition Source Under Hood

[Whoknows]

I'm installing a AmsOiler and I'm a near novice re: electrical mods. I'm wanting to tap into an ignition source under the hood. I've searched for this and can glean some general info (very helpful) for how to install my device, but I'm wanting to tap into the fuse box and am wondering if someone can help guide me to a circuit that is "switched" for power. I also know that some are "better" than others in terms of what Rando refers to as headroom. I'm obviously looking for the best one.

 

[Gangus2006]

Im not familiar witht he 4th Gen 4Rs, but you can poke around with a multimeter witht he ignition on and off and find a fuse thats off when the ignition is off, but on when the igniton is on, then use an add-a-circuit to trigger a relay. That would be the safest way to go about doing this.

 

[Whoknows]

Thanks for the input.

A few questions:

Can I pick up an add-a-curcuit from most auto parts stores?

I've seen this item in previous threads and have looked online, but am not sure if I completely get it. It plugs into the fuse box right? But, does it go in place of the existing fuse? And, then where does that fuse connect back in?