Erratic rpms Rotax 912/Garmin G3X

Jacques - tank you so much for this info!  From the looks of it, I would only need to add a ferrite suppressor on both ends of the line to my EIS.  I've never heard of one of those.

It will be easy to get to the side of the cable where the connector is, as it's right behind the engine.  But to get to the other side, right into the GEA24 engine monitor - ugh, I have to pull the windshield and instrument panel top cover!

But hey, I didn't go to all the expense to have something NOT work right!

I'll keep you posted!

Bert

My proposal is not "a cooking recipe" it is just a blockage, a filtering of parasitic impulses widely used in electronics.

Also try the resistance, recommended by Rotax, on the tachometer sensor coil.

The shielded wire is especially important to isolate the circuit counter from external disturbances ( radio, transponder, Bluetooth etc ...)

Use clip-on ferrites. (See both photos)

You can start with a clip-on ferrite placed near the motor's tachometer socket.

If you can, put the two white and blue threads in the ferrite, and making loops is even better!

Pay attention to the screw angles which must not damage the wires by the vibrations of the motor

I'm not a visionary, and if that doesn't work, don't blame me, I'm just trying to help.

I am a retired electronic technician and I have often fought parasitic disturbances!

Give us the solution when the garmin will work well and durably, it will be useful for everyone

Go, you will succeed !! ?

Jacques 

Hi all

I like Jacques idea, the diagram looks to be a good solution.  It is also important to check the wire routing and ensure that it is not near any high tension spark plug wires.  This really can disrupt your signal on the Rotax tach sensor feed to your instrument.  

Cheers

In my case, the tach wires are coming almost straight back towards the firewall, and are secured to the engine mount then through the firewall - point being, the tach wires aren't near any spark plugs.  Thanks though, good point!

Bert

Thanks Jacques, I actually went on amazon and bought 20 of these ferrite things/snap ons, of various sizes for only $8.  They should come today so I look forward to connecting them on.  I was actually thinking of NOT trying a wraparound because that's really wrapping them around very tightly, which I don't think would be good.  I do have the tach wires shielded, and grounded on just one side as per the Garmin directions.  I will keep you all posted.

vr

Bert