GRT EIS: High RPM Readings

[Pilotjim77]

My RPM is reading around 10,000 at low power settings and close to 20,000 at high power settings on the ground. I have a fairly new GRT EIS 4000 and older Horizon WS displays. RV-6 with an 0-320. Any thoughts on the cause? Can this be a settings issue?

[jclark]

There is a pulse per revolution setting that **MIGHT** be the cause.

Take a look at the documentation about that. It is different depending upon mags versus some electronic ignitions.

What engine/ignition do you have and what values did you use?

[Canadian_JOY]

Of critical importance to this discussion... You haven't provided any indication of how you are sourcing RPM data. Are you using a pickup that threads into the body of a magneto? Picking it up from the tach output of the P-Mag? This information is critical in troubleshooting.

[Pilotjim77]

Originally Posted by jclark

There is a pulse per revolution setting that **MIGHT** be the cause.

Take a look at the documentation about that. It is different depending upon mags versus some electronic ignitions.

What engine/ignition do you have and what values did you use?

Originally Posted by Canadian_JOY

Of critical importance to this discussion... You haven't provided any indication of how you are sourcing RPM data. Are you using a pickup that threads into the body of a magneto? Picking it up from the tach output of the P-Mag? This information is critical in troubleshooting.

Thank you for the replies. It is an 0-320 H2AD engine with the original magneto setup. I do not know exactly how RPM data is sourced as I did not install the panel. Also, I have gone through all the settings on the EIS but have not yet gone through the settings on the displays. Once I get to the display settings, maybe I will be able to resolve this. It just seems like such a high number.

[jclark]

Originally Posted by Pilotjim77

Thank you for the replies. It is an 0-320 H2AD engine with the original magneto setup. I do not know exactly how RPM data is sourced as I did not install the panel. Also, I have gone through all the settings on the EIS but have not yet gone through the settings on the displays. Once I get to the display settings, maybe I will be able to resolve this. It just seems like such a high number.

Looking at this a second time makes me think that your display might have a "decimal place"/'divide by 10" problem. Cannot remember off-hand and I cannot get to airport but check how these values are set to be DISPLAYED.

[BobTurner]

+1 on James’ post. I have this vague memory that if this data had a 4 letter name (‘tach’) it was assigned to decimal arithmetic, but a 3 letter name (‘RPM’) was assigned to integer arithmetic. Sure looks like you’re missing a decimal point, e.g., 1000 and 2000 rpm.

[Taltruda]

Originally Posted by Pilotjim77

My RPM is reading around 10,000 at low power settings and close to 20,000 at high power settings on the ground. I have a fairly new GRT EIS 4000 and older Horizon WS displays. RV-6 with an 0-320. Any thoughts on the cause? Can this be a settings issue?

Download the EIS 4000 manual. Pages 20 and 21 talk about tach signals. I wonder if your tach signal is set to the wrong value.

[Pilotjim77]

Originally Posted by jclark

There is a pulse per revolution setting that **MIGHT** be the cause.

Take a look at the documentation about that. It is different depending upon mags versus some electronic ignitions.

What engine/ignition do you have and what values did you use?

Originally Posted by Taltruda

Download the EIS 4000 manual. Pages 20 and 21 talk about tach signals. I wonder if your tach signal is set to the wrong value.

These posts sent me in the right direction. It turned out to be the Tach P/R setting in the EIS which was set at 20 for some reason. I reset it according to the table and it did the trick. Thank you very much for the helpful information.