'tweaking' rpm values

[RAFAIR100]

On a number of my downloaded aircraft, it is difficult to get the cockpit rpm gauge to give the value specified in the .air file.      On some occasions, the rpm cannot be effectively reduced using the rpm control, and can only be 'wound down' by reducing manifold pressure to unrealistically low values.     Can anyone suggest how to improve matters either by 'tweaking' the .air file or by using  fs edit.    

[ozzy72]

Have you adjusted the fuel mixture and prop pitch?

[RAFAIR100]

Thank you.     I was flying in 'automatic' mixture control mode which works well on most of my aircraft.   In 'manual' mixture, adjusting the mixture control seems to have more effect on the indicated rpm than adjusting the rpm lever.      But, at least, I can now get the settings somewhere near what I want.