where is bank 1 sensor 1 located toward the back or front of the engine i keep getting mixed up with these engines its a 2.7 liter and bank 2 sensor 1 thanks for any help

 

Bank 1 is the side of the engine with cylinders 1-3-5
Bank 2 is the side of the engine with cylinders 2-4-6.

The bank with the cylinder farthest forward is #1. look at our engine and you'll see which one is farther forward like exhaust manifold, spark plug etc.