As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4187 (MSP TO YYZ) CREW REPORTED THAT NR 2 ENGINE N1 TAKES MORE THAN 10 SEC TO REACH 50% ON TAKEOFF. THEY ABORTED TAKEOFF AT 20 KNOTS AND AIRCRAFT RETURNED TO THE GATE. ADJUSTED RIGHT ENGINE IDLE SPEED TO LIMITS IAW AMM 71-00-00. COMPLETED RIGHT ENGINE ACCELERATION CHECK IAW AMM 71-00-00. ACCELERATION TIME WITHIN LIMITS.