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Hey all, been slowly fighting this issue since May 2020, now going on 6 months I'm just over it. 2006 5.9 common rail. 6 speed manual trans. Smarty 90hp tune. DAP 75hp SAC remans.
Backround- started getting a clatter noise going down the highway with or without load. Definitely coming from engine. 2 weeks later cylinder 3 comes loose, scores cylinder wall with about a .030 groove. Time for rebuild.
I rebuilt the engine myself, all clearances look great. Head rebuilt at a reputable shop. Double/triple checked myself every step of the way. Injectors were sent to DAP for testing during rebuild process. They replaced 1 solenoid. Only issue found.
Among start up, it purred like a kitten, no issues at all. About 1500 rpm I have the exact same noise/clatter I had before it blew up last time. Is more noticable when engine is at operating temp. My first thought was injectors, back to DAP they went. All check good.
-Double/triple checked valve lash.
-push rods are straight.
-new sensors ( crank pos, cam pos, IAT, MAP)
- scoped all cylinders when injectors were out, no scoring. But some carbon build up.
‐idle rail pressure 7600psi
-unplugged fuel regulator and pump makes 27kpsi.
- capped fuel rail 1 cylinder at a time, could not determine if knock was present due to misfire.
I plugged in an oscilloscope and each cylinder is consistent with the others, but there is 2 injection events, do these have pilot injection?
Does pilot injection stop after a certain rpm?
Does anyone else have pics of the duty cycle and duration of their truck with an oscilloscope?
 

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Set your trigger level on the scope, then set it for single sweep (aka "norm" on your scope), fire it and snap a pic of each injector's waveform...

There are 2 events at idle and possibly a 3rd, would have to go back and look at my tune but pretty sure its just 2 at idle. the 3rd event is in & out depending on load.

I suggest getting a data logger attached to the obd port, preferably a good one that can log all the engine sensors and log the event. If you can get timing, rail, crank, cam, IAT & CT that would be good...
 

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Discussion Starter #4
Set your trigger level on the scope, then set it for single sweep (aka "norm" on your scope), fire it and snap a pic of each injector's waveform...

There are 2 events at idle and possibly a 3rd, would have to go back and look at my tune but pretty sure its just 2 at idle. the 3rd event is in & out depending on load.

I suggest getting a data logger attached to the obd port, preferably a good one that can log all the engine sensors and log the event. If you can get timing, rail, crank, cam, IAT & CT that would be good...
Steve, first of all thanks for the quick response. Friend of mine brought the oscilloscope over, maybe I can get him to come over again soon. I looked at all 6 injectors, and all fire the with the same wave form. Also all 6 have an intermittent 3rd event at around 1500 rpm. Which happens to be when I get my knocking clatter sound. This is done with no load. Currently I pulled the ecm off and going to have him reflow all the solder joints inside. Once we have that done I will post updates and more pics of each cylinder.
 

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stop... get the ecm back and reinstall it. get a data logger setup and log data. for all you know it could be a bad sensor causing this.
 
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