Knock voltage will determine alot. I place almost no faith in det cans either as I have seen motors with "no noise" be subjected to 35psi on pumpgas. A log still tells alot even if the tuner feels it is knock free.

Loose knock sensor will pick up more noise than a tight one.

A bad ground or defective knock sensor will do the same thing.

The shape of the voltage curve can tell stories as well.

 

Thanks John,now I know where to start looking...time to put on the work clothes.

 

Found the problem.Down pipe was right against the sump causing vibration and triggering the knock sensor.

 

That's great you found the issue. That is one of the reasons why I stress to make sure exhausts are not rattling against anything when attempting to tune.

 

Yeah I'm glad i found the issue.Luckily i had a new donut gasket and installed it so it pushes the downpipe down a bit.And this time i didn't clamp the downpipe as hard against the O2 Housing.