What was found
SHIP 188; FLIGHT 50 DIVERTED TO JFK DUE TO REPORT FROM SLC TOWER OF SMOKE FROM LEFT ENGINE ON TAKE-OFF AND FLIGHT CREW NOTED LEFT N1 VIBES HIGHER THAN RIGHT ENGINE N1 VIBES. EMERGENCY DECLARED ON ARRIVAL DUE TO UNCERTAINTY OF LEFT ENGINE AND OVERWEIGHT LANDING. CORRECTIVE ACTION: MAINTENANCE INSPECTED INLET, EXHAUST, AND CHIP DETECTORS WITH NO FINDINGS; THEN PERFORMED HIGH POWER RUN AND N1 VIBRATION WAS WITHIN LIMITS AT 1.9 UNITS.