From your paper (The illustris simulation: Public data release), you mentioned that the primordial solar metallicity is 0.0127. Could you tell me which reference you cited? However, the solar metallicity of Anders & Grevesse (1989) is 0.0189, and the other lower values are 0.0134, 0.0133. Isn't your value too low?
This value is e.g. from Wiersma+ (2009), where it is described in some detail where it comes from.