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Discussion Starter · #1 ·
Have not posted in many years but a frequent viewer. Unbelievable knowledge base here. My 05 6.0 has an intermittent hot no start condition. I recently had my Warren built 155's rebuilt and upgraded to the lifetime stiction cure solenoids. Prior to this I had a stiction problem and difficulty starting in cold conditions. Upon reinstallation, the stiction problem was gone but I immediately developed a hot no start condition. The truck runs great otherwise. I have noticed that when the truck gets hot enough, it develops a miss at idle. If you shut it off at this time, it will not restart. If there is no noticeable miss at idle, the truck will restart. Soooo…, went through the whole process. Shop air leak tested, no leaks found. Replaced nipple cup seals, injector seals, standpipes, dummy plugs, and ipr to no avail. No noticeable change in hot start problem. I have had the truck apart 4 times now and starting to pull my hair out. Can a faulty injector or 2 cause a hot no start? Any suggestions would be much appreciated.

Cold Cranking IPR Duty Cycle-84%
Hot idle IPR21-24%
Cold Cranking ICP-500-700 psi
Hot cranking ICP-300-350 psi
Hot Cranking IPR-84%
No leaks detected shop air 150 psi 30 minutes ipr commanded closed valve covers off
HPOP 50,000 miles WOT 3500-4500 psi
LPOP 50,000 miles
 

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It's amazing what a crap injector can do to these trucks.
What is your ICP, IPR, RPM, and fuel pressure when hot no start?
You many just need to get a contribution test done if the above are all good.
Could be as simple as a bad injector connection..but.....
 

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Discussion Starter · #4 ·
No noticeable misses cold or hot when running down the road. Misses just at hot idle. Have not done a contribution test at hot idle when missing. But hot cranking icp is roughly 350 psi, ipr at 84%, fuel pressure 70 psi, and RPM good (don't have specific number). Is there any way hot high pressure oil could leak from anywhere below the injector top seal? Seems like a bad electrical connection would show up hot or cold or on a buzz test.
 

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Did you do the STC fitting? When you're leak testing it, are you doing it when the engine is hot?

Try looking here at around 8:45. Should watch the whole thing though.

 

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350 psi is not enough to start... ad 84% means its maxing out to make enough pressue.

Jason's DTR video will help.
 

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Dang phone--didn't see his numbers posted.
 

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Discussion Starter · #8 ·
STC was already updated when I put the HPOP in. This problem literally came on right after I reinstalled my injectors. It just seems too coincidental to have something else occur that was not related to the injector work, like the standpipes or rail seals or injector seals. That is why I replaced all those things. The miss at idle only when hot leads me to believe the leak is at or close to an injector. Yes I did leak test while somewhat hot. Had cooled enough to remove valve covers. I used to think hot no starts were a relatively easy thing to diagnose, I was wrong!
 

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Watch the video Jason posted its a big help
 

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Discussion Starter · #10 ·
Anybody else experience a miss at idle only when hot? Thanks Jason, good video, he seems pretty dead set on not messing with rail seals or injector seals. I had original rail seals the first time I put this truck back together after injector rebuild. Had the hot no start, replaced stand pipes and dummy plugs first, no improvement, next replaced rail seals, no improvement, then replaced all injector seals, no improvement. Again, the problem started immediately after I put the new injectors in. Before new injectors no "hot no start" problem, no miss at hot idle. After new injectors, hot no start, miss at hot idle. No misses at cool idle, no codes, no miss at hiway speed. Seems pretty expensive to buy new rails and new set of injectors to see if that is the problem.
 

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It seems like it has to be an injector seal leaking. Did you use OEM seals? Are you leak testing at the ICP and both sides? You must be hearing/getting some air from the back of the pump if you are.

Look here at 10:55, not sure if it helps :dunno:

 

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Discussion Starter · #12 ·
It appears that I have one or more leaking spool valves in the injectors themselves. Hence, the hot idle miss. Pulled injectors and sent them in. I will post if that corrects the problem.
 

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Discussion Starter · #13 ·
Sent the injectors back to warren. They repaired them and they are working nicely. Cured the hot no start. It seems that we need to add leaking spool valves to the list of hot no start issues.
 
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