Engine Throttle Always High During Auto mode

I am flying 2000mm wingspan trainer fixed wing with a gasoline engine fitted with Pixhawk Cube (Plane 3.8). Issue I am facing is of Throttle during Auto mode which stays at high always. During descent waypoints specially auto land though altitude decreases but speed gets abnormally high crossing over 45m/s. Cruise speed is set to 20m/s but it never locks on that speed and mostly fly at over 30m/s.

Already done airspeed sensor calibration, even tried disabling airspeed sensor and used GPS alone. Did tuning of pitch and roll but still not getting any success.

Can you advise all parameters that affect the throttle functions just incase i have missed any crtical one.

the most common issue that causes this is a reversed throttle servo. You may have both RC3_REVERSED and SERVO3_REVERSED incorrect, so it is OK in MANUAL but wrong in AUTO.
Please post a log to be sure.

Here is the link for logs.


That log doesn’t include any time flying. It is sitting on the ground.
Please upload the dataflash log of it flying.
Cheers, Tridge

Hi Tridge,
I have a similar problem with my plane: in auto modes like rtl, loiter, auto, my plane accelerates to speeds significantly higher than the configured trim_arspd_cm. Also throttle is higher than trim_throttle. I have throttle on channel1 but neither rc1_reversed nor servo1_reversed is set. Where could this come from?