Ill try to keep it short and to the point. I had a nelson 93 tune and my truck ran pretty good except for a lottt of spark knock. I tried several different brands of gas and still got the "marbles in a coffee can" sound. So this has been going on a while decided i would just re tune the truck back to 87 and say the hell with it. Well did that like a month ago and it pings just as bad even on and 87 tune still running 93. I wanted to eventually do some long tubes and what not but now im thinking about going back stock or lighting an f'ing rag in the gas tank.(i would like a new 6.2lol ) Any help is greatly appreciated

 

first off, are your knock sensors functional? next, it sounds like you need an in person tune or at the very least some datalogging so nelson can see what your truck is doing and adjust the tune as necessary...that's the biggest problem with mail order tunes is the tuner can't see what your particular vehicle is doing, they can only go off of what they've experienced with most similar vehicles.