B757-200
Flight Crew Air Transport Pilot (ATP)
Distraction; Confusion; Troubleshooting
Aircraft Equipment Problem Critical
Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Aircraft
Experienced asymmetric thrust on climb out. FO was PF. EPR (Engine Pressure Ratio) gauges were aligned but N1; EGT; FF; N2 were all 30 to 40 percent apart. We selected manual throttles and to balance the symmetry of flight. We could not increase the left engine without overshooting the max EPR. At that point the left engine was max EPR and all other gauges where reduced from the right engine by 30 to 40 percent. We leveled at 10;000 ft and observed very little thrust to accelerate or climb. Observing our lack of thrust we elected to return to ZZZ. At this point Maintenance speculated a bad PT7 probe on the left engine.
B757 Captain reported that during initial climbout the Number 1 engine failed to produce normal thrust. The flight returned to the departure airport.