I'm trying to bind the A/P Engage CMD to my joystick but I can't figure out what key is bound to it.  I'm in P3D and I've looked at all of the keys listed for Autopilot but there doesb't seem to be a default key mapped to the command???

Unless they've changed it in P3D, the default FSX keybind for the A/P master was "z" although I thought for sure it was listed in the controls section.

Best to use the PMDG Options for keycommands. This is one that is set there and not in the platform, although in this case it might pass through.  You definitely need to use the PMDG Options for A/P disconnect for that to work properly.  I have mine set to Shift+Ctrl+Z.

 

See also the Introduction document that covers all these nice to know things.

Thanks guys for the help, got it sorted now.