I noticed that there are a number of articles on this problem that still don't seem to have been solved. I observe, on my jet, with the modern flight model that, by taking altitude, the consumption does not change (whereas it should decrease), and the number of RPM increases, whereas they should remain stable...! My engines.cfg file specifies use_old_fuelflow_simvar=0
In a jet, there is always, even on the first generation engines, a reagent which maintains the number of revolutions at an optimal speed according to the ideal mixture... This does not seem to be the case here, and I do not see any variables allowing to specify whether or not this regulator exists and is operational!
Thanks to the Asobo team to tell me if this is a bug, or if there is a way to fix my problem!