What was found
PDX FLT 9851 THERE IS A SMOKY BLEED AIR SMELL COMING FROM AIR CONDITIONING VENTS AFTER ENGINE START. SMELL EVENTUALLY CLEARS OUT. OPERATED BOTH ENGINE BLEEDS AND AIRCRAFT PACKS TO PURGE POSSIBLE CONTAMINATION. NO OIL SMELLS OR OTHER UNUSUAL ODORS NOTED AFTER REPEATED RUNS AT VARIOUS POWER SETTINGS, BLEED FLOW SETTINGS AND TEMPERATURE SETTINGS. NO PARTS REPLACED. AIRCRAFT OK FOR CONTINUED SERVICE.