Knock that isn't knock

[white92tsi]

What factors (other than actual knock) could cause .4 degrees of knock to be registered?

I have been tuning with ECMLink and am seeing .4 degrees of knock in the upper RPM band. Adding fuel and removing timing are having no affect. I know it's not a real issue (most tuning guides suggest tuning for anything less than 2 degrees of knock)

What other issues (maintenance-wise) could be causing the knock sensor to see .4 degrees of knock when it seems as though it's not actual knock (removing timing and adding fuel doesn't take it out).

I'm thinking:
Motor Mounts
Carrier Bearings
Half-shafts going out

Are these correct? Anything else that you guys have seen?

Thanks.

 

[Turboturd]

Those things are all possibilities, but the sensor itself is searching for frequencies that can occur from normal engine harmonics. That's why a minimal amount of knock is expected and the stock ecu doesn't pull timing at counts that low