What might cause an intermittent, metallic clicking like sound around the pedals/bottom bracket?

I have a bike, with a pincher style eccentric bottom bracket and with a Shimano alfine crankset.
In high torque situations, sometimes you can hear a metallic clicking sound, but not always.
I have regreases and tightened the bottom bracket assembly. There is no play in it, I have the correct amount of spacers installed.
Could it be the pedals? They seams to be alright.
What can I do to make it dead silent?