score:8
Yes, you can go to Istanbul with your ID card.
Generally speaking, Kris is right, you do need a valid passport, even for countries for which you don't need a visa.
But in this case, you can in fact enter Turkey with your national ID (see this official page from the Turkish ministry of Foreign Affairs and the relevant page from the Italian ministry of Foreign Affairs mentioned by Geeo). This possibility is only offered to citizens from a few countries (not the whole EU) but it's the case for Italian citizens.
Citizens from an even smaller list of countries can also enter with an expired passport but that's not the case for Italy.