1. turn it 3 whole revolutions (1 revolution = 360 degs) anticlockwise.
(anticlockwise = the side away from you when you hold it goes to the left, the opposite to what the hands on a clock do)
2. Put the Auto into 1st gear, Drive it 400m down a straight road giving it bursts to exactly 4500rpm and see if it opens goes "pssht~"
If its still not doing what you want it to, then repeat step 1 and 2 again.
If you loosen it too much the top will spring off the BOV and you gotta screw it back on again. Its not difficult if that hapens.