ok so last month i was getting blue smoke when under boost only with boost. so i replaced both turbo. still was getting smoke so again i replaced the turbos. no change so i replaced the pvc the valve seals. i have no oil in the inner piping. only other thing left is piston rings ? also getting knock sensor codes check the wires and sensor couldnt find anything wrong with them only comes on when i get on the car at highway speeds please help