Need some help with an 08 Cummins 6.7l. The truck was tuned 6 months ago and had been running with no problems until about a week ago. The owner said the truck started smoking black any time he was on the throttle and occasionally he would get a fuel knock along with white smoke. Initially though he had a failed injector so he took it to a local shop and they checked balance rates and they indicated no. 2 and no. 5 out of spec. He had all of the injectors replaced. When he picked the truck up it started and ran normally until warmed up and then started having the same issues as before. Then thought maybe the tune was the culprit. Flashed in a known good file and had the same results black/white smoke along with fuel knock. No codes. Logs show every thing is running in normal ranges. Timing, Pulse, TP%, etc. all normal. No post duration as the tables are zeroed. Im at a loss here any help would be greatly appreciated. Thanks in advance.