What was found
STRONG BURNING ODOR THROUGHOUT ACFT FOLLOWING START OF LT ENG. NO SMOKE PRESENT. APU BLEED ON. ISOLATION VALVES OPEN. PACKS OFF. REMAINED STRONG BY EXIT ROWS. NOTICED STRONG OIL ODOR FROM NR 1 ENG EXHAUST WHEN FIRST ARRIVED AT PLANE BUT NO SMOKE. NO OBVIOUS SIGNS OF OIL LEAK NOTED. PILOT REPORTS NO VISUAL SMOKE, BUT VERY STRONG ODOR OF BURNT PLASTIC. ODOR DISSIPATED RUNNING PACKS, ODOR REMAINED STRONG AT OVERWING EXIT ROWS. ON INITIAL IDLE RUN LT ENG IAW AMM 71-00-00, BURNING ODOR NOTED IN COCKPIT BUT DISSIPATED WITHIN 10 SECS. PERFORMED OPS CHK TO DETERMINE CAUSE OF BURNING ODOR IAW AMM 05-51-56-940-801-C1, STEP 1.D.4-21. NO BURN ODOR NOTED. ISOLATED APU BLEED, RT ENG BLEED SOURCES, LT & RT PACK, & BOTH RECIRC FANS. NO BURN ODOR NOTED IN ANY CONFIGURATION. PERFORMED PACK BURN OUT IAW AMM 21-00-21-102-030 2.C.9.C. NO BURN ODOR NOTED.