I've been having a strange brake issue for the past few months. My brakes work just fine on my daily commute to work (no interstates, only one red light I have to stop at). However the other day I was on the interstate in stop and go traffic, (where you usually have your foot on the brake at all times), and when I go to brake, the pedal goes all the way to the floor and there is no stopping power at all. But if I let off the pedal completely then push it again, they work fine. And this is all random. 9 times out of 10 it will brake just fine but every once in awhile it'll go to the floor with no brake power. Same with fast food drive throughs, parking lots, and anywhere where you on and off the brake frequently. I've bled the brakes, and done everything else I can think of that would be causing this. Anyone else have this problem or know what would be the issue?

Thanks

 

Sounds like the master cylinder.

 

I had a similar issue with my 2015, pedal wound sometimes got to the floor. My issues was heavily worn pads on the rear, apparently would cause the cylinder to push so far out it would cause it.