Connect the coils, injectors and ECU power supply to the same PDM output

[troy4ou]

Hi, I'm putting together the harness for my PDM 08 and I'm just with the outputs.
The idea that comes to mind is to connect it in the following way:

25A fuse for air compressor paddlesifth
20A fuse for fuel pump
15A fuse for water pump
15A fuse for fan water
15A fuse for ECU power and MME power, coils and injectors + keypad
15A fuse for vtec
15A fuse for rain light
15A fuse for engine starter

The question I have is if the 15A fuse for ECU power and MME power, coils and injectors will be enough with 15 A and if there is any problem like interference or strange things.
I think I'm not forgetting any other 12v connection on my k20a2 engine

[Adamw]

Yeah that will be fine and is usually how I do it.  Its best to have coils, injectors and ecu connected to the same supply so the ECU batt voltage measurement is relevant for correct deadtime and dwell time.

Vtec & rain lamp could probably be combined to free up an output depending on how the rain lamp is controlled, but both are likely less than 1A draw total.  

[troy4ou]

14 minutes ago, Adamw said:

Sí, eso estará bien y es lo que suelo hacer. Es mejor tener las bobinas, los inyectores y la ECU conectados a la misma fuente de alimentación para que la medición del voltaje de la batería de la ECU sea relevante para el tiempo muerto y el tiempo de permanencia correctos.

Probablemente se podrían combinar Vtec y la lámpara de lluvia para liberar una salida dependiendo de cómo se controle la lámpara de lluvia, pero es probable que ambos consuman menos de 1 A en total.  

The rain lamp would be controlled by a button on the keypad, so I see it as unfeasible to have the VTEC and the rain lamp on the same PDM output.
The idea is to not have any normal fuses and relays in the car.

Thank you very much for the help, it's a pleasure to build these projects with ecu link

[troy4ou]

17 hours ago, Adamw said:

Sí, eso estará bien y es lo que suelo hacer. Es mejor tener las bobinas, los inyectores y la ECU conectados a la misma fuente de alimentación para que la medición del voltaje de la batería de la ECU sea relevante para el tiempo muerto y el tiempo de permanencia correctos.

Probablemente se podrían combinar Vtec y la lámpara de lluvia para liberar una salida dependiendo de cómo se controle la lámpara de lluvia, pero es probable que ambos consuman menos de 1 A en total.  

Adam, what is the ampere consumption of the coils and injectors of a K20 engine?
And what is the ampere consumption of the fuel pumps?

[Adamw]

Injector current will be relative to duty cycle.  The normal rule for high impedance injectors is to allow 1A each for the worst case scenario of 100% duty.  

For coils in direct spark mode there will only ever be one charging at a time, so although the wire needs to be large enough to minimise voltage drop at peak current, from the perspective of the source you only need to allow for the average current, my guess would be <5A average for the K20 coils.  

Fuel pumps vary hugely, both with pump model and pressure required.  Typical road car sized pumps at typical pressures I would say 15A would be common.  But it is not uncommon to see ~25A with some of the bigger flow models at say 600kPa.  Many manufacturers will have published current vs pressure graphs, otherwise if unsure you are best to test yourself.