As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BEFORE TAXIING CREW EXPERIENCED SMOKE ENTERING THE CABIN AFTER ENG START. SMOKE WENT AWAY WHEN RT ENG BLEED AIR WAS TURNED OFF. CREW IMMEDIATELY SHUTDOWN THE ENG. PERFORMED ENG RUNS WITH CREW. ENG BLEED & ENVIRONMENTAL SYS WAS OPERATED & NO DEFECTS WERE NOTED. ACFT WAS RETURNED TO SERVICE.