In installed a TT Vapor, and I can't get the tach to function properly. It continuously shows much higher than the what it actually is. I tried changing the PPR count from 1, to 2, and even the .5 mode but still it shows far too high. I wired the red lead for the tachometer function to the black/yellow wire directly on the coil, and then ran the black lead into the same place I grounded the power feed for the unit. I know it is probably something simply-or at least hope it is! Can anyone offer me any advise?