A few months after having my engine rebuilt I started hearing a sort of "off-tone" in from my engine. Its between 3-4K and sounds like something is loose or catching inside. My car sounds different before and after, which I thought was to do with the cam (standard) which made the engine a lot sweeter at top end.
What Im concerned about is that Ive not had it retuned since the rebuild as it was tuned a couple of moths before going in, will it need doing again? Another thing is I got one of those ecotek things and thought that might be causing it, although Im not really sure. After reading an ecotek post, Im just hoping its not running lean... infact it might be the other way. Does a rebuild need a retune and what could possibly be casuing this differance in engine tone?