闭门造车

Explanation: Car made behind closed doors. Metaphor from reality, but relies on subjective things. 　　Usage: -Linked; as predicate, attributive, adverbial; containing derogatory, used for criticism, advice 　　Source: Song Xi, "or ask" Volume V: "The old so-called 'behind closed doors, out Hezhe', cover with the words of the law." 　　Examples: Since that ~, out of the Hezhe, and had made outside of the rut of their car, whether the results coincide. (Fu "Salvation decision theory") Thesaurus:  to cover up one's faults and refuse to listen to counsels, Whitewash, hide one's sickness for fear of treatment, cover up one's errors by excuses, smarted up