I doubt you'd find many if any "injection molded" parts in a modern turbofan engine. The technologies used to make the parts are pretty universally high-tech and often state of the art. In the hot section, you'll find some pretty amazing technology used for both the turbine blades and nozzles - things like single crystal or directionally solidified part to eliminate or minimize grain boundaries in the parts. Fan blades used to be forged/machined solid titanium - however with the introduction of wide cord blades, the weight of solid TI became prohibitive - which lead to developments like the hollow fan blades used by Pratt and Rolls and the carbon composite used by GE.
3d printing is advancing rapidly, but I suspect we are still a ways from widespread use of 3d printed parts in commercial turbofan engines. When things like grain boundary's become critical to the performance and life of the part, 3d printing has a long way to go.