I'm taking a guess on having a broken rocker, what's your guys thoughts? 08 F250 6.4l. It's got a dpf and egr delete, sct tuned with IDP custom tune. I noticed a sounds coming what seemed to be threw the intake, a popping sound, also I can hear some tapping/rattle on the passenger side valve cover area. Runs fine otherwise, buddy thought it ran to well to be broken. It's got 136k miles. But It seems to have a lot of blow by for the truck running this well. I just bought this truck at an auction, got a crazy good deal on it. So I wasn't there when this sound started. I'm leaving town for a week and won't be able to work on it, but when I get back depending on what I find out ill tear the valve cover off and look at it.