Is this efflorescence?
Is this solid masonry or is it a "Thin Brick" system?  

Due to the uniformity of the appearance, that does not look like Efflorescence to me.  It looks more like some sort of surface treatment added to the brick during the firing process or an acid treatment. These bricks have similar appearance...

http://www.glengery.com/brick-products/view-brick-products/item/1415186-bayhill-thin
http://www.glengery.com/brick-products/view-brick-products/item/16-cherry-lane

I'm not sure what you are trying to clean.  My suspicion is you've power washed the intended finish off of the surface of the brick.  I would do some homework...


Can you find the product literature for the brick by contacting the
builder? 
Contact a local sales representative from a major brick
supplier (the Belden Brick Company or Glen Gery for example) and ask
for input - they should be able to tell you exactly what the brick
is, what it's supposed to look like, and how to treat it.


Try to find out what it's supposed to look like and how the manufacturer recommends you clean it before trying to treat it.  And i would choose a more discreet test location next time.