Hi

A customer brought in a FC S4 and a he purchased the Banzai adapter harness and a FDS4 PFC. I have nothing bad to say at all about the kit offered by banzai. Its all being thought off and if you follow the guide nothing can possibly go wrong.

Its just that I didnt really have a stockpile of FC trailing coil packs and also I did not like the idea of using only 1 channel of both 2 channel ignitors.

Therefore I designed a small PCB that fits inside the PFC case. It features some period correct 40 and 74 series logic gates and it converts the 2 trailing outputs of the pfc ecu into a IG-t and IG-s signal that works just fine on the stock FC trailing coil pack/ignitor. More then likely people being into electronics will find a better and/or more efficient way to realize this but yes.

For those also having time to spend or lack of FC trailing coils I attached the gerber files of the PCB and some pictures how to wire it up.

So the procedure is simple. in the pfc there are 3 ignition channels. Its a transistor driving a FET which switches the wire to the FD ignitor to 5v rail. After the FET there are 3 big 150 Ohm SMD protection resistors. R126 is front trailing, R150 is leading and R135 is the rear trailing. So what I did was remove both the trailing resistors (R126 and R135). The side of the resistors at the connector side needs then connecting to the pin 5 and 6 of the PCB (R126 to IG-t and R135 to IG-s). The 2 remaining pads are the T1 and T2 signal of the pfc and this simply go to T1 and T2 (pin 4 and 3).

Conviently the Banzai adapter harness has the T2 pin of the pfc already connected to the IG-s input of the ignitor.

then one also needs 5v and ground. this can be fetched form the big regulator located at the 9 o clock side of the PFC (connector facing up) pin 1 is GND and pin 3 is +5v rail.

parts required to build the PCB are
CD4001
CD4027
CD4050
74HC(T)32

4x 1k resistors for R2-3-8-9)
2x ceramic 4.7 nF (C4-5)
3x some other capacitors just to make sure the 5v rail on the board is nice and stable. might be overkill but yes.
1x 6way JST 90* header and matching female plug. one can also solder the wires directly on the board or use any other connector to attach the wires from the PCB to the PFC

optional: 4x 3mm LED's and 4x 2k2 resistors (in case you want some LED's on the PCB for R4-5-6-7)

here is a short movie in slow motion of the thing in action.
Dont have too many photos at this time but in a couple of weeks I need to do another install so I will try to get some more.

 

if i were to do this do you think the car could run smart coils? i have a s5 tii with power fc so the trailing pack is modded but i want to switch to smart coils and am not sure if it would work

 

For smart coils you do not need this. As the pfc has 3 ignition outputs already. Split the leading so you run wasted spark there and direct fire on the trailing.

the pcb could be modified in case you would like to run direct fire and not wasted spark on the leading also.