Knock reading

[scottsnissan]

WEll It started today.Had my Safc hooked up for 4 days now.Knock was at 0 at and idol and might get 1 after acc.Well today leaving work wasent looking at it till about half way home.Was reading 150-200 idol.So when i got home i looked once more and read 108.So basicaly what would be my first move here?Could my sensor be bad?There is no irregular noise other then a very small valve tap,I mean smallHave to have ur ear on the valve cover.But nothing from the lower end.

91 240sx red top sr20detstock besides test pipe and exaust.And soem others but not motor wise.Always ran stock boost.