Have you ran the lead to the second P-Mag?
Try removing the additional filter to see if the filter is damaged.
Remove the signal line and tap it to +12v and see if you get pulses on your EFIS.
You could switch to the 5v signaling (install diode) and move pin 33 back to pin 32.
Alternatively, our 71420 RPM Interface board allows for a dual P-Mag installation using Pin 32.
Just a quick update. Adding a ground from the Pmag to the airframe brought back the tach signal but it still oscillates as before. The next step will be to try a 5 volt signal to pin 32. I will report back on this thread.
john
Added diode for 5 volt signal and changed input to pin 32. No joy. I am looking for an "Aha" moment where all of the symptoms come together.
Symptoms in cruise:
RPM +/- 50
Noisy EGT and CHT
Fuel flow +/- .1
All of the other guages are stable - oil pressure, oil temp, fuel pressure, volts, amps, etc.
Other anamolies:
On landing, EGT#3 becomes eratic -1276 to 475 in 30 seconds.
Looking over the RPM wiring, where should pin 31(White/Orange) and Pin 16(Black) go when using P-Mags?
john
Lets start with the EGT / CHT noise. Are the sensors from an upgrade or from AFS? If you disconnect the crimp terminals and measure ohm from each lead to the probe case are you getting any readings below 5MΩ? If they are they probably need to be replaced. Try leaving any out of spec probes disconnected and testing for noise.
Those can be removed or capped off.Originally Posted by johninreno
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