The GRT EIS is the engine monitor. All engine data goes to that device as a data collection point and the is sent to the displays via serial communication. The GRT EIS gets its RPM information from the "P" lead on the mag. The most common reason for the RPM flucation with the GRT EIS is the protection resistors on the P leads. Read through the install manual and see what they recommend for resistor values and probably increase the value. Look for the resistors by the mag or by the firewall interface plugs. If you need further help, let me know off line.


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Jon Hadlich
AI Systems
(541) 815-7381