PID tuning on larger quads?

I am being told that my problem with my quad lies within the control loops of the flight controller. That being said I am not able to fly my quad to tune it. So where do you start with tuning. Before I lengthened my arms and up’d my motor size from 2214 to 4114 the default values were “ok” at least to get the quad up in the air and get it tuned. The way mine sits now with the default values it is impossible to fly. Motors get hot and you have to constantly be correcting some kind of extreme movement.

I went from a 550 size to right at 750. Went from a 12in prop to a 15in prop. I reset the pixhawk back to default settings and reset everything up from scratch. I have not even touched the control loops It was always my understanding that the default PID’s would be able to get the quad up in the air. Do I just need to set everything to zero and go from there?

Would inductance in my Power to ESC wires be causing me this issue? I did extend those wires almost 5 inches.

I had a user over on RCgroups tell me that my issue sounded like an ESC problem and we got to talking about the 2 settings I changed with BLheli. I moved my Demag Compensation up to high and my motor timing to medium high. He suggested I turned down one of them. I originally changed those parameters due to a little stutter. Anyway, I moved demag back down to the default of low and my problems has pretty much vanished. I am still going to install better larger value caps on my ESC just to be safe. Got some good Nichicon Low ESR low Impedance caps to go in place of the cheapies that are on there. And I still have to tune the thing. We will see what the end result is.

Hi, I have a Hexocopter running motors 4014-320KV and with 15’ props but it is quite uncontrollable. So I was wondering who you got on?