From BiblePortal Wikipedia

King James Dictionary [1]

Enquire usually written inquire, which see and its derivatives.

Webster's Dictionary [2]

(v. i. & t.) See Inquire.

International Standard Bible Encyclopedia [3]

en - kwı̄r ´: This is an Old English word now obsolescent. It is common in the King James Version. In the American Standard Revised Version it is nearly always replaced by the more modern "inquire," a few times by "seek" and "ask," once by "salute" ( 1 Chronicles 18:10 ). With this one exception in the Old Testament the change does not affect the meaning. In  Acts 23:15 , "enquire something more perfectly" is substituted by "judge more exactly." In  Matthew 10:11 , "search out" replaces it. In  Matthew 2:7 ,  Matthew 2:16 , "learned exactly" replaces "inquired diligently." See Inquire .