As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AS POWER CAME UP FROM IDLE A BANG WAS HEARD AND LT ENG REMAINED AT IDLE PWR. NO CONTROL OF LEFT ENG FROM COCKPIT. NO ENG EXCEEDANCE NOTED AND NO INDICATIONS IN COCKPIT OF ENG FAILURE. ENG WAS NOT SHUTDOWN FOR EMERG LANDING AT JFK. FOUND METAL IN TAILPIPE. ENG REPLACED.