No full throttle in AUTO takeoff

when I try to hand launch my plane in AUTO mode, it doesn’t seem to take up 100% throttle at the take-off waypoint because of which i don’t feel like launching it as it is lacking enough thrust and lift (fyi I’ve set TKOFF_THR_MAX = 100 and take-off alt = 8 ft.). But when I lower my plane a little and bank it right, it suddenly reaches to 100% throttle. I’ve successfully completed accel and compass calibrations as well.
I guess either the accelerometer or the magnetometer is malfunctioning, though I’m not able to figure out the exact reason.