So at some point this season, my tach (Gaffrig) on my 271 fastech started reading high consistantly across the board. High at idle, high at WFO, high all the time. I figured it was the unit giving up the ghost and needed to be replaced....until this past weekend. This past weekend jokingly with my wife, I tapped the glass on the gauge, and low and behold, it started reading correctly, but eventually it would go back to reading high. Not sure what in the world would cause that, other than maybe a loose connection? I plan on pulling the dash panel tomorrow and seeing if there is something obviously wrong. So OSO any ideas on what would make it read right after tapping on it. Oh and Gaffrig is no help, their phones are only open a few short hours most days (must be nice to sell a product then say EFF YOU CUSTOMERS NO SUPPORT).

Maybe the selector on the back is between the 6 cylinder and 8 cylinder detent?

Yeah that was my thought as well. Planning on checking that for sure.

The dial on the back had moved slightly. Put it back to 8. Will see if that fixed it this evening.

Awesome!! Easy fix.....hopefully!!

Turning the dial back to center on the 8 seems to have fixed the problem. No more reading high! That was super easy.

I have the same issue. I hope my fix is the same!