B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Total 19385
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Regained Aircraft Control; Flight Crew Rejected Takeoff; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
I had to reject the takeoff; below 80 knots; due to the number 2 engine not reaching the target N1 and not producing the requested/required thrust for takeoff. We were planned for a MAX-SPCL; 26K; dry runway; bleeds ON; flaps 25 takeoff on Runway XXR at ZZZ airport.I was the pilot flying this leg. When we were cleared for takeoff we were told cleared for immediate takeoff/no delay; traffic on a 3 or 5 mile final. I took the runway; advanced the throttles to 40% N1. When the engines had stabilized I pressed the TOGA switch and the throttles advanced. I quickly noticed that the number 2 engine N1 had not reached the target N1 but the number 1 engine was already at its requested target. I gave it about another second or two; and realizing it was not producing the required thrust I rejected the takeoff. We were definitely below 80 knots; as the First Officer had not called '80' yet; but I don't recall the exact speed.We cleared the runway and I advised the passengers and flight attendants that we had a minor engine problem that we had to check out and that I would get back to them when I had more information. We reviewed the rejected takeoff procedure; RTO considerations; and the brake cooling schedule. We concluded that no special procedures were needed as we had rejected the takeoff below 80 knots and when we used the brake cooling chart we fell safely in the 'no special procedures required' zone. The First Officer and I then discussed what had just happened. All engine indications at this time were now normal. I felt that maybe because we were rushed due to the landing traffic on short final and that this is a much shorter than normal runway that maybe I rejected too soon and didn't give the engine enough time to 'spool up.'  Maybe we could attempt another takeoff; perform a full static run-up of the engines this time to give the engines the best chance of achieving normal/required thrust and this time we would not be rushed and would be ready/expecting what to look for. The First Officer agreed and he coordinated with the Tower while I made a PA to the passengers and flight attendants explaining briefly what had happened; that all appears normal now; and that we were going to attempt another takeoff but that we would not continue if it wasn't safe.When we were cleared for takeoff the second time the number 2 engine did the same thing and only achieved approximately 85.4 N1 while the target was 99.2 N1. We rejected the takeoff again below 80 knots.We cleared the runway and while the First Officer coordinated for taxiing and parking; I made another PA explaining to the passengers and flight attendants that one of our engines wasn't working properly and that in the interest of safety that we could not continue the takeoff and flight to ZZZ1. An aircraft maintenance logbook (AML) entry was made while also reporting the malfunction to the dispatcher and  maintenance. The number 2 engine was not working properly and not producing the required thrust for takeoff.
Captain reported two rejected take offs caused by the number two engine not reaching target N1 speed.