tune up vs tune-up

tune up is not a noun while tune-up is a noun.

Word	Noun	Adjective	Verb	Adverb
tune up	No	No	Yes	No
tune-up	Yes	No	No	No

tune up (noun)	tune-up (noun)
	adjustments made to an engine to improve its performance
	exercising in preparation for strenuous activity

tune up (verb)	tune-up (verb)
adjust the pitches of (musical instruments)
adjust for (better) functioning