Truck at high 900rpm idle does a normal idle noise then for maybe 4-5 cycles kind of acts like a surge but rpms don't move. It's kinda like it fires all the cylinders 1 right after another type sound you cant really hear it in the engine it's more or less it's more in the vibration it sends through the exhaust. I can somewhat replicate by barely tapping the accelerater over and over. Only difference is I make rpms move.
Sounds like a harmonic vibration and probably nothing to be concerned with. Does it do it at any other rpm?
Can't hear it at 775 idle but both my 900 and 1100rpm high idles do it
I have a 2350 at about 900rpm I don't like the sound it makes. Seems like it is in a unbalanced state.
Might be the turbo doing a cleaning cycle
Could be idk just seemed out of place. Next target I'm going after is why I get a noseful of crank case fumes every time I use engine brake to slow down. Used to think it was valve stem seals but now with new head still does it. Maybe a turbo seal but I would think over a year of it I would think the bearings would have dynamited. As it barely has anything coming out of crank vent at idle but idk under load. Can't catch that perverbial tail I'm chasing.
flex-pipe behind the turbo not installed properly / cracked? - seen that a hundred times on prostar.
Could be cracked hard to tell since it's the woven wire style
Smoke a cigar around the pipe and see if it blows away.