Hi I’m new to powerstroke very familiar with the Idis but I bought my first power stroke maybe three months ago it is a 1994 with about 240,000 miles on it four-wheel-drive and five speed manual transmission when I bought it I couldn’t hear anything out of the normal just sounded like a power stroke but maybe after 100 miles or so I could hear this pinging and knock sound at idle. Then I could hear it while driving down the road but if the windows up you have to really listen for it and know it’s there to hear it. I change the oil and the fuel filters and could be just my paranoia but it seems to have gotten louder after that as well as now I think I have a few injector O-rings out because it smokes blue on start up and goes away after 30 seconds or so. The sound is very similar to what people call injector knock, and after watching a few videos of that knock it sounds identical to mine, but the only difference being is I can hear it while driving and supposedly injector knock goes away while driving like I said, I’m new to these power strokes, really hoping I didn’t buy a blown motor. Any help would be appreciated.