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Discussion and questions related to the course Practical Motorsport Wiring - Professional Level
HI all. I hope you can help me as this is my first time wiring this type of coils. I'm Piggy back wiring an EMU Black ECU to Ford Expedition 1998 5.4 L and I used 22 awg wires for the trigger pin on the coils and didn't touch the stock 12V 18 awg wires going to the coils. I'm not sure if this type of coils will need a bigger size wire for the ignition trigger pin on the coil as I don't know if there will be current passing through this wire or not. Usually there's a power supply pin, at least one ground pin, and one ignition trigger pin but these coils only have 1 pin connected to 12 V and the other connected directly to the stock ECU so I'm afraid that using 22 awg wires will damage the ignition output terminals on the EMU black or worse
Also since the EMU black wiring will splice into the sensors' signal wires and will only control 8 ignition coils and 8 injectors, I wired the primary power supply to the ECU and ECU ground of the EMU black using 20 awg wires. As for all power grounds and the switched 12V pins, I used 22 awg wires. Should I have used bigger size wires?
I appreciate all the help I can get and Thank you in advance
If the coils have only two wires, they are passive (dumb) coils. If one has constant 12V and the other goes straight to the ECU this means the factory ECU has the required ignition drivers built in. According to the EMU Black documentation the ECU is only capable of driving six of these style coil directly, not the 8 you require; running 8 directly will damage your ECU. The ECU can support 12 coils with in built igniters (smart) coils or 12 passive coils via a separate ignition module. Both wires for the coils will need to be 18 AWG but trigger wires from the ECU to a separate ignition module only require 22-20 AWG.
According to the EMU Black documentation, it has two H bridges and a wideband controller on board, so the 12V power supply & the power grounds would want to be 18-16 AWG depending on what is being utilized. I don't see any recommendations in the EMU Black documentation for their recommendations, however I have attached some documentation from a Motec M150 which has some helpful recommendations for wire sizing (see page 3).