driven87

iTrader: (1)

ok guys i have a ultra lite autometer tach that was working in my freinds 6 cylinder car. i snipped the brown and orange wire and hooked the signal wire into my fast XFI harness wire that states "tach out" on the wire. started it up and the tach and idling at like 2k when the XFI box shows 800. tried hooking it back up in 8cylinder mode and it reads 1500 at idle not the 800 it is. what am i doing wrong here? is there any other place i can get a signal from on the harness like a coil or something? did i do it right by snipping those 2 wires? just looking for direction to get this installed correct. thanks guys