about half the time my truck is idling i get a really bad diesel knock. it sounds like a 97 ford PSD except not as load. but it just knocks pretty bad. my rpm's are the same and nothing else seems to change. just the sound of the truck. the other half of the time the idle is the smooth regular duramax sound the only mods i have is a juice, banks exhaust, and a drop in K and N filter

Did you check to see if maybe something came loose on the exhaust or elsewhere? Fuel filter changed lately? Had a dirty filter on a Mercedes diesel and it knocked at idle sometimes unitl I replaced it.

the filter is good and it is coming from the engine the exhaust is fine. the filter was just changes 1000 miles ago.

so is this normale or not?

I have heard from several different people that lately, they have experienced the same thing - 2 were Cummins. Speculation is quality of the fuel. One was going to try a fuel additive to see if it helps. During a period of time when I didn't regularly run additive in the fuel, I would have the same problem with my '02. I haven't had it happen for some time, and it is even quieter running B20.

It could be a bad injector on a 02 it's a very good possablety.

i would think fuel as well but it dosnt happen all the time. i am hopping it isnt an injector. i am also thinking something is bogging down my engine.

Injector