We present comparisons between numerical simulations of Fe II emission spectra and HST high - resolution and signal - to - noise spectra of the Eta Carinae Weigelt B & D blobs . The spectra show a wealth of FeII and [ FeII ] lines . We investigate the dependence of the spectrum on electron density and on pumping by blackbody radiation . Using the photoionization code Cloudy we were able successfully reproduce the fluxes of few hundred FeII & [ Fe II ] lines in the range from 4000A to 6000A. Fe II emission analysis in Eta Car ejecta is very important because it provides information about excitation conditions , the electron temperature and density solved in a selfconsistent way . Moreover , for the first time we were able to use Fe II emission analysis itself to put limits on CNO abundances in emitting regions .