Tach reading in the 4500 has become very unstable, fluctuating wildly and randomly, and pegs at 3000 for much of the time. The analog tach remains stable and true. I assume that this is more likely to be a faulty sensor (AFS/magneto) than an EFIS problem, and ask whether replacing that would be a logical next step.
Kenneth Melvin
RV-9A, Hillsboro.