FAST B2B TFI wiring problem on Mustang...

[Jeff S]

I'm having some problems with a FAST bank to bank TFI setup on my car with an MSD Digital 6 ignition.

According to the FAST instructions the white "points" wire connects to the points input wire on your aftermarket ignition system, if you are using one. Also, according to FAST I am supposed to connect the 2nd wire from the bottom of the TFI clip to negative coil lead or points input on ignition system.

The problem I have is that according to the MSD instructions I cannot connect any other wires to the negative coil lead except the black MSD ignition wire. If I connect both the FAST "points" wire AND the 2nd from the bottem TFI wire to the MSD's points wire the car will not start.

If I leave the FAST "points" wire DISCONNECTED and only connect the 2nd wire from the bottom of the TFI to the MSD's points wire the car starts up fine.

Is it ok to leave the FAST "points" wire disconnected?

 

[TurboTR]

Yes- if I recall correctly the wire from the TFI module should be all that is needed. If you had no TFI module and were using the MSD by itself, then you would need the FAST points wire connected to it.

In this case the FAST drives the TFI module with an EST signal (SPOUT in F*rd terms); the TFI module then drives the MSD.

Now that I think about it, I'm not sure if you should have some sort of pullup on that TFI output or not. In the stock setup, the coil primary can act as a pullup. Replace that coil primary connection with an MSD box and not sure. If it starts and runs fine that way, then so be it.

Alternatively, you should also be able to leave the TFI module output wire disconnected from the MSD and instead just drive the MSD directly with the FAST points wire...

Hope that all makes sense

TurboTR

 

[Jeff S]

Makes sence! I have left the FAST "points" wire disconnected and begun tuning. Now I just need to figure out why there is a MAJOR dip in power... car makes 665hp at 5900...450hp at 6200...and 640hp at 6500!