What was found
FLT 517, BOS -JFK. ON TAKE OFF ROLL SHORTLY AFTER ENG 1 STARTED, DIRTY SOCK SMELL PERSISTANT IN COCKPIT FOR ABOUT 5 MIN. NO DEICING ON PREVIOUS LEGS. INFLIGHT DID NOT NOTICE ODOR. PERFORMED FIM REF 21-22-00-04AAA-423A-A, UNABLE TO ISOLATE ODOR, DUPLICATE ODOR EVENT AFTER RUNNING APU, LT PACK, RT PACK, ENG 1, & ENG 2. NO ODOR NOTED. ACFT OK FOR CONT SERVICE.