Around last fall I went to ohio on a camping trip with my buddy and his family. I live in maryland and on my way out my brother and I heard a light knock sound. We thought it was the CD in the radio so I backed the song up and then we didnt hear it. Then we heard the worst sound come from the engine. The knock followed the beat of the engine but, very loud. I looked out my mirrior and the cars on my right slowed down because they couldn't see. White smoke poured out of the tail pipe and I pulled off the first exit. I called onstar and they ran a engine check and it came up good. So up the road we went and bam the noise was back. I had to pull over again and found a truck stop. After dumping a bottle of fuel additive in it, it never made the noise again. When i made it home I called the dealer and he told me it must have been a small piece of dirt in one of the injectors and that the bottle of additive lubercated and cleaned it out. He said I did no damage and it would be ok. Could that one case be a early sign of the famous injector failer? My truck is a 02 D/A 3500.