What was found
UPON T/O, SMELLED UNKNOWN ODOR. DURING CLIMB, IT DISSIPATED AND CAME BACK A FEW TIMES. AT FL 260, DECLARED A PRECAUTIONARY EMERGENCY. WHEN POWER CAME BACK DESCENDED, THE FUMES WENT AWAY AND DID NOT RETURN. ALL THE WAY PACK TO EWR, IT SEEMS TO COME AND GO W/THROTTLES. RAN ENGINES AT VARIOUS POWER SETTINGS UP TO TAKEOFF. POWER EPR IAW B727 JRH CH 4 AND 7-15 WITH BLEEDS ISOLATED AND ALL OPEN, CYCLING PACKS HOT/COLD. NO NOTICEABLE ODORS IN COCKPIT AT THIS TIME. CHECKED GASPER FAN, OPS NORMAL, NO ODORS. CHECKED MDC COMPARTMENT FOR POSSIBLE SPILLS, NONE.