has anyone used an FD CAS on an FC?
 

specifically the FD CAS with a stock based FC ecu?

i did try it, and it didn't work, and i decided that since the FD CAS's are higher impedance than the FC pickups, it doesn't work.

but then isn't it an AC voltage signal?

it does work the other way, as we know, the FD ecu will run either the FD or FC cas.

Since the ECU has an amplifier for the cas signal, you'd have to somehow physically change the input impedance of the circuit inside the ECU which would require a single or maybe double component change depending on how the signal amplifier is designed. I would suspect that the FD ecu has a much lower input impedance than the FC ecu thus allowing both CAS to work on the FD ecu.

Follow traces, take your ECU apart, and bust out the multimeter. You'll also need an FD ecu for reference or at least information on its input impedance.

i suspect you are exactly right, i also suspect changing hardware is too much work (for me).

Out of curiosity for someone with an aftermarket ECU what benefit or gains can be had swapping the FD into an FC?

the FD CAS is more accurate, as its a crank trigger, and doesn't have the drive gear of the FC setup. its also easier to setup, as there is only one way to assemble it, its not adjustable like the FC is.

Or get an FFE trigger wheel and toss it on the FC and call it a day.
Works with an aftermarket Ecu such as the PS1000 but I am not sure of stock FC ecu though.

Styx I was just curious because my plan is to go FFE wheel and Hall sensor but I wanted to keep the AC and PS so after speaking with Billy I realize some modification will be needed in order to accommodate for the (thicker)wheel and sensor combined with my Touge Factory pulleys

According to FFE you cant retain A/C because the hall sensor bracket mounts on the studs where the a/c would normally attach to.

The bracket uses 2 bolts/studs on the front cover to hold it on the engine.
I've seen a thread where a member has cut a PS pulley and retained the placement of the Trigger wheel to make the system work.

My car is bare bones..no a/c or PS.

Like Styx(and Billy at FFE) said it's been done before, I removed both systems on previous builds but because I'm in Charleston now I will need to retain the AC. Black on black+ summer(s) in Charleston=AC