i got a buddy with a 2001 3500 6.6 lt dmax, he was pulling a trailer and all of a sudden his truck started knocking hard and pouring out black smoke. we checked the glow plugs to see if they were wet but that was a dead end. we put a little computer up to it and it showed no DTC's and there were no check engine lights on either. im not sure what else to check for. anybody have any suggestions? anything mentioned would be greatly appreciated

 

check the MAF sensor on the intake tube to see if its fouled or dirty, then i would check all the intercooler tubing and boots, sounds like your not getting enough air... leads me to believe that you have a blown intercooler boot or something along those lines

 

ill be sure to check those. checked it out last night though and we are think that one of the injectors is stuck closed just not positive yet but ill check the intercooler tubing and boots tonight

 

if a injector was stuck closed it would not be over fueling and blowing smoke. i think britewhite is right about the boots for it to be that sudden. these inter coolers have plastic plugs that can blow out and cause boost loss also so you might want to get that checked out also. how does it run at an idle without boost? i think it might be unlikely but i would check your turbo out also pull the intake hose off and check for damage to the impllar and see if it has much movement. it should have some give up and down but not much. as long as its not hitting the housing it should be fine

 

If he had a boost gauge he would know 100% right away, but what your describing to me is loss of boost, lots of black smoke and no power... that points to air issues