When driving on the interstate, right at 80 mph and 2500 rpm the engine will start knocking. Then if i ease off it a bit it will knock a few seconds more then its quite. Any sugestions? (Injectors, fuel pump, motor wore the f out)

2004.5 3500 Dually
270,000 k Miles

Slow down????

Seriously though, I believe it has something to do with pilot injection. Don't think it's a problem

Not an issue, pilot injection as stated above. It will just rattle like that.

Add a little less than 1 once to a gallon of fuel of 2 cycle outboard oil. Mine used to do it too then it stopped when i started adding the 2 cycle oil. There is a hole article in here on the lubricity of the fuel and adding additives. I use the cheap walmart brand.

Can't do this on newer models though because of the emmison stuff.

No more pilot injection at 2500 RPM therefore it rattles.

pilot injection is off @ 2500 rpm. One help is to run stanadyne fuel additive. It raises the cetane rating and will reduce the knock. In mine, with the fuel around here, it reduces the knock considerably. almost the same as with pilot injection. BTW, the info on pilot injection shutoff is in the manual.

weird that you just started noticing that at 300000 miles.

Cool. Glad to hear its not a real problem. Will try the fuel additive and maybe slow down a bit. :D