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Choosing injector wire size and PDM Channel

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Hello all,

I am in the process of building my S14 with LS3 swap. I plan on running the Haltech NEXUS R5 in it and am wanting some input. I am pretty sure I will be fine running 22gauge wire from each injector output straight to the injectors from the Haltech, but am questioning the power wire design. I was going to run 18ga from one of the 8 amp channels then split into 8 22ga wire to power each of the 8 injectors. I feel this wiring will be more than sufficient, just wanted some more input to make sure this will be fine. I also wanted to make sure the 8 amp channel will be sufficient for the injectors. I am running 65 lbs Deatschwerks injectors. The resistance of the injectors are around 13.6 ohms, which puts the amperage at 14.7V at 1.08 (.99 amps at 13.5V) using ohms law. Will the 8 amp channel be sufficient for running these injectors? the 4 25 amp channels will already be tied up by coilpacks, fans, and primary fuel pump.

Thank you,


8 amps will be fine as they aren't at 100% duty cycle. My normal wiring for a V8 would one 18 ga wire for each bank, then splice that into 4 wires for the individual injectors. Splice the two 18ga wires into your PDM output. BTW, if you need more current, just combine two channels splice the outputs together and you'll have 16 amp capable circuit. Just make sure the condition that turn on both outputs are the same.

Awesome! Thank you, that helps out a lot. I am still playing around in the Nexus software and haven't found out how to combine 2 channels for one purpose. I am positive there is a way to do it, just haven't found it yet. I am rewiring the entire car and of course I have decided to make it the most daunting task possible by wanting an autosports quality harness, rather than a club level type harness. I have the majority of the tools necessary to do the job, such as DMC AF8 and AFM8 crimpers. Still takes a great deal more planning. For the level of this vehicle, I know I can get away with creating a club level type harness, but I already have the tools, I feel like I have majority of the knowledge and drive to go the extra mile.

Again, thank you for your input!


Edit: I will figure out how to split each bank into a separate channel in an effort to allow for future upgrades. I will update once I figure out how to do that within the software..

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