Help diagnose my miss please

J

junkyard dog

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Oct 15, 2012
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So little back story about truck. It's an 05 with nv5600. Truck has set of BD r700 compound, T&C pump, Flux 3.5s and a Fass 150. Injectors were sent to F1 when truck had ~134k and now has 140k. I must say that truck never started or sounded so smooth or quiet since I've owned it. Approximately 2500 miles later truck developed a miss( what I describe as a chop in the exhaust). It started this after I pulled off highway after running approximately 65-70mph for 2 hrs. Also when you clutch truck it runs under idle setting to about 550 then back up to 900ish and does this till it settles on 750 rpm. I have replaced all three injector harnesses due to one rubbing on a stud double checked that crossover tubes were torqued and installed per spec and also solenoid nuts. This was all done at time of injector install and like I said truck ran great for a while. Truck doesn't have any blow-by and runs awesome at anything above 1000rpm. I've double checked valve lash a couple times for the thought of cam lobe problem, push rod or valve but no change since lash set at time of injector install. I have used a scan tool to kill injectors one at a time and it sounds the same always. Truck doesn't seem to be making oil or getting poor milage. After lots of searching I decided to swap FCA and it didn't help. I'm about out of ideas and would greatly appreciate any help.

Thanks and sorry it's so lengthy.
 
Not saying this is it but something to think about. I had a intake rocker go bad an it did sort of the same at idle u could hear it was a little off but it still drove fine. That was until it got worse then it finally threw a cylinder misfire code.
 
Cummins6.7trip said:
Not saying this is it but something to think about. I had a intake rocker go bad an it did sort of the same at idle u could hear it was a little off but it still drove fine. That was until it got worse then it finally threw a cylinder misfire code.
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its sound valve train related which is why ive looked at valve train several times. I may pop cover off and take a peek ASAP and see. Ive had another truck bend a push rod and valves get out of adjustment before but this has me stumped so far.
 
If you think it's in the valve train, I would do a compression and leak down test. That would rule out a vavle issue or at least tell you if everything is seating up properly. I always do a compression test with the engine cold. Sometimes if there is a slight problem it may not show up if the engine is warmed up.
 
Well mine had me stumped to an that is the worst feeling but if you get the rockers off agin just give the pins a close look, cause I missed mine the first time. The rocker worked good in the middle rang of pivoting but if I pushed it all the ways in either direction it would stick just enough to mess stuff up. Good luck hope this helps.


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Cummins6.7trip said:
Well mine had me stumped to an that is the worst feeling but if you get the rockers off agin just give the pins a close look, cause I missed mine the first time. The rocker worked good in the middle rang of pivoting but if I pushed it all the ways in either direction it would stick just enough to mess stuff up. Good luck hope this helps.


Sent from my iPhone using Tapatalk
Click to expand...


I will definitely give it some attention. Thanks for ideas. And a compression check is probably in the near future.
 
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