RPM showing about double the actual number

[Cap_Ax]

My RPM read is showing about double than expected. For example, Idling my engine shows 1500~ which is obviously off.
This is a new install so still figuring out configurations, setup and troubleshooting.
Have me missed anything that needs to be setup?

Thank you all!

 

[Rhino]

What type of engine do you have, and what type do you have entered in the Skyview setup?

 

[Rhino]

If this is the Cessna you mentioned before, you might want to review one of your previous threads.

First flight - a few squaks

I know this is probably In the documentation but I am tired of reading :) I am hoping I can get some pointers to troubleshot installation issues VS configuration issues. This is a Cessna Cardinal 180 Horse Lycoming 0-360 1) fuel flow seems too high 2.3 gl/hr on idle and 12.5 on cruising. My...

forum.flydynon.com

 

[Cap_Ax]

If this is the Cessna you mentioned before, you might want to review one of your previous threads.

First flight - a few squaks

I know this is probably In the documentation but I am tired of reading :) I am hoping I can get some pointers to troubleshot installation issues VS configuration issues. This is a Cessna Cardinal 180 Horse Lycoming 0-360 1) fuel flow seems too high 2.3 gl/hr on idle and 12.5 on cruising. My...

forum.flydynon.com

Lycoming IO-360 thats what I entered.

 

[Cap_Ax]

Thanks Rhino, while that previous post from July was helpful. I am still having the same issue.

 

[Rhino]

These are tough because Dynon does not sell tachometer transducers, they vary per engine, as do connection locations, and they don't all indicate the same way. I'd verify the pin connections and rules beginning on page 7-46. Do you have the 30k resistors installed? Have you gone through the calibration process?

Other stuff to look at:

Erratic tach readings

While flying yesterday, my tach readout on my Dynon Skyview started going crazy…. rpm were jumping all over the place between 2600 to 4000rpm! It did this for about 10 minutes and then returned to normal for the last 10 min of the flight. The Dynon EMS is connected to the right mag only,( Have...

forum.flydynon.com

RPM sensor SkyView sytem

Is there a sensor for RPM reads for 1966 Cherokee six 260 lyconing 0-540? SkyView engine monitor system.Thank you

forum.flydynon.com

 

[Rhino]

Oh, and hope for someone with more experience to join the conversation.

 

[Dynon]

The engine type doesn't affect RPM at all. The two things that can, though, are either the pulses/revolution setting being set too low (when it's reading too high), or possibly noise from the magneto that might require a higher resistor installed above the normal 30k one that is normally employed.

Nominally, for RPM that's being read off a conventional magneto, the settings are:

4 cylinder: 1
6 cylinder: 1.5

 

[rjones560]

My RPM read is showing about double than expected. For example, Idling my engine shows 1500~ which is obviously off.
This is a new install so still figuring out configurations, setup and troubleshooting.
Have me missed anything that needs to be setup?

Thank you all!

The type of ignition system you have does matter. With magnetos you need the P lead pickups and wire each tach input to a magneto with a 30K resistor so that you don’t lose your tach during magneto checks. The software needs to know how many pulses per engine rotation to read properly. This is different on a 6 cylinder vs a 4 cylinder engine.
I have EMag Air Pmags now that have a tach generator that works great, but I ran dual Bendix mags with the P lead pickups when I started flying my RV10

 

[cbennet12]

The engine type doesn't affect RPM at all. The two things that can, though, are either the pulses/revolution setting being set too low (when it's reading too high), or possibly noise from the magneto that might require a higher resistor installed above the normal 30k one that is normally employed.

Nominally, for RPM that's being read off a conventional magneto, the settings are:

4 cylinder: 1
6 cylinder: 1.5

Semi related question. Helping a buddy with a new Dynon install, mag on left, EI on right so he’s on pin 32 on L and 35 on R. No RPM showing up on either. On the mag side he has the 30k ohm resistor on the P lead just before the key switch vs after the switch on the line to the EMS.

Is that a problem?

thanks!
craig

 

[rjones560]

Semi related question. Helping a buddy with a new Dynon install, mag on left, EI on right so he’s on pin 32 on L and 35 on R. No RPM showing up on either. On the mag side he has the 30k ohm resistor on the P lead just before the key switch vs after the switch on the line to the EMS.

Is that a problem?

thanks!
craig

You should specify which electronic ignition. There are very different solutions depending on which one you have. On the P lead pickup you can put the 30K resistor on the switch on the P lead side, but not in series. One side of the resistor to the switch and the other side to the tach pickup for the Dynon. Remember that when you ground the mag with the switch that it will also kill your tach output for that mag. That’s why if you have 2 mags you need the tach output for both so you won’t lose RPM when you turn one of them off. The Emags have a dedicated tach output that works with the Emag turned off.

 

[cbennet12]

You should specify which electronic ignition. There are very different solutions depending on which one you have. On the P lead pickup you can put the 30K resistor on the switch on the P lead side, but not in series. One side of the resistor to the switch and the other side to the tach pickup for the Dynon. Remember that when you ground the mag with the switch that it will also kill your tach output for that mag. That’s why if you have 2 mags you need the tach output for both so you won’t lose RPM when you turn one of them off. The Emags have a dedicated tach output that works with the Emag turned off.

Thanks for the feedback. For the moment I was prioritizing the mag reading because it’s the “simplest”. He currently has a Lightspeed III on the low voltage input on the right side. I’m hoping to talk him in to moving that to the high voltage line from the key for consistency. i have that exact setup in my RV6 and it has worked flawlessly.

craig

 

[cbretana]

Had exactly the same issue with my O-320 when I first installed p-Mags. They provide spark plug pulse at top of power stroke and at top of exhaust stroke, so you get two pulses every revolution, instead of only one. The extra spark plug pulse at the top of the exhaust stroke apparently doesn't affect the engine. You have to adjust the configuration setting that controls how many pulses per revolution Skyview expects to see.

 

[-Bob]

"Remember that when you ground the mag with the switch that it will also kill your tach output for that mag."

According my my log files, that is not the case. I see exactly the same values for RPM L and RPM R under all conditions. Neither value drops to zero during a mag check. I have two Bendix magnetos on an O-320 engine. The two tach sensor leads are connected to the P-leads at the ignition switch, via a resistor. The switch is known to work correctly and does ground out the P-lead when switched off.

I think this is a bug in the way the log file is recording the data.

 

[Dynon]

Yeah, I think that's a quirk in the data log output, if I remember correctly.