On a GA plane, the mixture stays at 0, can't move can't start the engines. Then I decided to fly the airliner this being 737, a350, e jets and so on. I thought it would work since there is no "mixture" levers in the airliners. To my surprise I can't start the engines after pushback, so I did some more research on the topic. I found out that there are people who experienced the same issues as me in the ssg e jet, they said it was a problem with their mixture controls. So I decided to debug my mixture ratio using the X-Plane feature at displays the values of the mixture on the top left corner. When I move my lever up the value increases for a split second before falling back to 0. I'm trying to fix this issue with assuming it would make the engines of my planes being able to start again, or at least make the GA planes flyable.