I need someone that can talk me down.

I need the help from someone that can help me analyzing a flite log. I have a problem with a pixhawk mini. it will suddenly accelerate straight up for some reason until I have to chop the throttle and then it will drop and throttle back up very slowly.making a uncontrollable yoyo flite. very hard to land safely.
I can extract the flite log.but I dont no how to post it.

I need someone that can talk me down.

You need to put in a cloud storage service somewhere (Dropbox, etc) and post a link to it here. It’s the .bin file we need. You may as well describe your craft also (components, power, all-up-weight).

3dr pixhawk mini ,3dr gps, frsky-x4r receiver in 16ch mode,multi star 8000 4cell batt, 3 emax blheli 30amp, esc’s,on a 3lb 7oz tri copter fame, frsky horus tx using both internal and external antennas .
I’ve logged many sable flights with this copter in the past.

Your Z vibrations look high, that will be a problem for sure. Check prop balance and any wires transferring vibrations to the flight controller.

You Vcc (5 volts) for the flight controller is too low and you should seriously check the wires and connectors, even look at replacing the power brick or whatever you’re using for supplying the FC. This could also be affecting other devices such as the GPS and causing those glitches.

I’d start with those things, then retest and post another log.

I also found this.
Some Pixhawk Minis have a hardware defect that makes the internal MPU9250 IMU unreliable.

  • The problem is only present in older hardware revisions, because it was fixed at some point by the manufacturer.
  • To check whether a specific board is affected or not, leave the board disconnected for some time, then power it on and try to start the mpu9250 driver from the PX4 command line. If the board is affected, the driver will not start.
  • The MPU9250 is disabled by default on the PX4 firmware.
  • The defective Pixhawk Minis will not calibrate without an external magnetometer or an attached GPS, even indoor.
  • When using an external GPS, this is not a problem because the secondary ICM20608 provides the accelerometer and the gyro, while the external GPS provides the magnetometer.do you know what the symptoms are for this , my unit is pretty old.

You are quoting PX4 Flight Stack info and you are using Arducopter. In Mission Planner on the Mandatory Hardware>HW ID screen what MPU is shown. Or just post the screen shot.