I got a used xtune rpm guage (GA-XT-TM375-W-CF) and hooked it up. red, white, and, black are connected good no problem. the green I plugged into 2 different spots and there was no reading so I ended up putting it into the blue ignition coil wire. now it works but is showing 5k rpm at idle. the guage is working properly other than that and goes up and down when rpms go up and down but it thinks it's way higher than it actually is. there is settings on back of guage for 4,6,8 cylinder and it was on the 4 so I don't know if it's because the guage is old and it's been dropped or if it's an issue somewhere else. any thoughts or similar experiences??