Engine Knock please help
 

I have a 04 lly and just before it shifts right when the engine starts to unload it has a knock like a rod,but it comes and go's,it knocked for 2 miles this mornin and then stopped,i drove it 100 miles with no problems and then after it cooled down for about an 5 hours i got in in and drove it and it didnt knock,but after about 2 miles it started doing it again,anyone know whats going on,any help would be great .thanks, it has a bully dog and a cold air kit and thats it.

Pull the BD off and see if that affects it...
what kind of knock is it? Is it smoking more than usual? have you checked the oil?

not smokin at all,going to take the BD off today,it really sounds like a rod knockin but it comes and go's and i have never heard a rod come and go.just changed the oil 1000 miles ago and its full. Can a fuel knock sound like a rod or main knock.

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Its got engine code,p1093,p1094,p1621, does anyone know what those are??

p1093: Fuel Rail Pressure Low During Power Enrichment
p1094: Fuel Rail Pressure Low During Idle or Decel Fuel Cut-Off (DFCO)
p1621: Control Module Long Term Memory Performance

Have you changed your fuel filter lately??? these codes lead me to believe that you may have a clogged fuel filter

I know the fuel filter is stopped up for sure,i been runnin some old fuel thats been in a tank for a year,but will that cause a knock in the engine???

change your filter ASAP and have a spare one handy, these Common rail engines HATE bad fuel, you can damage a lot if your fuel is bad, I change my fuel filter with every oil change, it sounds like your engine is starving for fuel, that could be where your knocking id comming from

Change your fuel filter often, dirty fuel will kill a common rail engine fast, In fact if your running bad fuel it might not be a bad idea to get an inline filtration system like FASS, or Airdog, or Nicktane, or XX, just extra insurance on your $400 a piece injectors, and your $10000 engine

Our current tunes knock pretty hard on a cold motor.. mine sounds like a old ford when its cold..

the new tunes im building have no cold engine knock. at least on my truck.

Sometimes it knocks on a cold day but i been running the BD for over a year and this was totally different,it sounded just like a rod or main,i changed the filter and took the BD off and put about 300 miles on it since and never heard it again,BD is going back on tomorrow and if i hear anything its going to be traded.

what version is your downloader at?

2.4.1 I think, i didnt put the BD back on yet and heard the noise again today for just a second while i was gettin on the freeway,it knocked for about 10 seconds and stopped