Why do color values change when the ICC-profile is changed? Shouldn't stay the color values the same but look a little bit different based on the profile you are looking at? For instance i have a greyscale picture which is only in the colour black when i look at it with the coated FoGra39 profile. But as when i change the profile to let's say coated FoGra27 the same picture is suddenly cmyk? Why does this happen?
If you selected No Conversion, the simulation in Acrobat will behave the way you were expecting: i.e. the values in the PDF won't change, but the Simulation Profile you select will change how it appears on the screen accordingly.
If you selected Convert to Profile (Preserve Numbers) - Do Not Include Profiles, the numbers won't change.
If you DID include Profiles, then it's forcing Acrobat to match Profile to profile appearance wise, and that involves changing the numbers.
This may be moot in many situations anyways, as there are usually settings to preserve greyscale blacks at RIP stage (even in Acrobat's Adavnced printing dialog)
1. FOGRA39 is a CMYK profile, and any colour will be converted to that profile, using the info in the profile.
2. It doesn't matter if your original is greyscale only, there is no exclusion from the conversion.
3. The way conversion happens is this: the original colour is converted to Lab using the input profile (whatever it is, you don't say). Then the Lab colour is converted to CMYK using FOGRA39. Like most CMYK colours, it generates rich greys from Lab greys.
Converting between CMYK profiles ALWAYS loses carefully assigned plate assignments, which can be a disaster of course. This is why workflows need to be carefully planned.