High RPM withour engine running

[Remy]

Hello everyone
I have this issue with HDX 1000 and Pmags installed, since I have wired them: with main battery ON, and Pmags ON, engine not running, EFIS shows 10300 RPM !!
I put diode on both Pmags
Any idea?
Thanks in advance

 

[soarhead]

Interesting. I have dual P-Mags and was getting the same issue from the right P-Mag only. Since Dynon allows being wired to both P-Mags, that is what I did. Then when I isolated it to only the right P-Mag, I disconnected that tach wire and the issue seemed to go away. Then one day, I powered up and it was doing the same on the remaining left P-mag. As soon as I started the engine however, it went back to normal.

So E-Mag says that while they supply tach information, it is not officially supported, so I haven't asked Brad about it. My next step if I see it again, is to move the prop slightly while the Mags are grounded to see if it goes away. My thinking is that it might be resting on point where a pulse is being sent. Sort of like when the LED flashes rapidly during timing checks because the mag is teetering on a pick up point.

 

[Rhino]

Oops.

 

[bugsy63]

Hi Remy
i experienced the same issue but with one P-Mag and it was solved by turning the prop a
few degrees.
Might be worth a try.

Regards
Michael.

 

[kurtfly]

If the PMag / prop is positioned right at 0 deg it is possible that one or both IGN’s are toggling because it is positioned so close to the decision to send out the tach pulse. So, as Michael said above just move the prop a couple degrees and it will stop. i have seen this a couple time before.

kurt

 

[Guenin]

I will second what @kurtfly and others have written above. It's a very predictable behavior in my plane. When the prop is positioned such that the PMag's LED is green, then EFIS will show a nonzero RPM, my oil pressure warning will go off since the EFIS thinks the prop's turning with no oil pressure, etc.

 

[Remy]

Thank you for replies
When moving engine by hand, discrepancy disappears

Have a good day