The tacho reading bouncing around at readings over 5,000 rpm was quickly solved by Googling some forums and then finally (duh!) reading the Dynon manual page 7-47. They recommend installing a 60k ohm resistor between the engine trigger coil and the Dynon EMS pin 32. I put together a used 100k ohm resistor (all that I could find in my small town) and that did the trick, until it failed, when I found another pilot who, miracle of miracles, had dozens of new resistors that he was only to happy to share. Finally, an easily resolved problem
