Pete Rose -- Takes Lie Detector Test ... Will New Commish Buy It?

Pete Rose desperately wants the new MLB Commissioner to believe he's not a liar, because the disgraced baseball great just underwent a polygraph exam ... TMZ Sports has learned.

Multiple sources tell us Rose went to Jack Trimarco & Associates in Beverly Hills on Wednesday to take the lie detector test ... and it's all connected to his efforts to be reinstated.

Rose wasted no time reaching out to Commissioner Rob Manfred when he took the MLB reins this year. According to Manfred, Rose has filed a formal request to have his lifetime ban lifted. We're told Rose is hoping the polygraph results will help him build a case for Manfred.

Reversing the ban would be the first step to Rose possibly getting on a Hall of Fame ballot.

Trimarco's pretty famous in lie detector circles. He's worked on terrorism cases like Oklahoma City and the '93 World Trade Center bombing. He's also the guy who truth tested Jose Canseco about steroids in baseball.