What was found
NR 1 ENGINE TREND DATA SHOWS AN INCREASE IN DELTA EGT AND DECREASE IN EGT HOT DAY. FUEL FLOW AND CORE SPEED REMAIN STABLE. GROUNDED - YES. PRIOR TO RUNNING THE NR 1 ENGINE, TOOK A LOOK AT THE EGT PROBE READINGS AND OBSERVED THE S4 ALTERNATING FROM DASHES TO READING 1349 DEGREES. ACCOMPLISHED T49.5 PROBE AND EGT SYSTEM INSPECTION REF AMM 77-21-01-200-801-F00. FOUND THE S4 PROBE TO HAVE HIGH RESISTANCE. REMOVED & REPLACED S4 PROBE REF AMM 77-21-01-400-801-F00. ACCOMPLISHED EEC TEST REF AMM 73-21-00-700-804-F00. OPS CK GOOD WITH NO FAULTS. NO FAULTS ON FLT LEG 0.