OldIron82
Full Access Member
Hello all. I’m about to rip my hair out. My 6.9 idi… Ive been dealing with this intermittent slight miss that has varied in intensity since January of this year. Right before this began, I installed a new 100cc injection pump from a very reputable shop who shall remain nameless, I don’t want to cause bad feelings. On the truck’s maiden voyage, a 300 mile trip about 200 miles into it something freaky happened. The engine started rattling so loud it sounded like you turned the pump fully advanced, and then went another 1/4 turn while activating the cold advance simultaneously. I mean, LOUD rattle. At idle it was loud, and having your foot into it doing highway speed, it was loud. Just babying it kept it relatively quiet but oh my dear lord a highway marked at 70 mph doing 40 was not fun. Got to my destination, let the truck sit overnight and the next day it fired right up and ran like nothing happened.
Now, about a week later this mystery miss began. I’ve tried isolating it, swapping injectors, cracking injector lines. I pulled the valve covers, all rockers where they supposed to be. I even ripped off the entire top of the engine to replace the lifters, as I surmised the old lifters might not like the new Comp 910 springs and possibly a valve wasn’t being allowed to fully open properly. Still nothing. Now just last night I threw in a complete set of different injectors out of a engine that purrs like a cat. STILL misses and now it’s really pronounced. They are stock injectors, the injectors I had in were stage 1 injectors from another reputable performance shop.
I’m clueless. But starting to seriously wonder if whatever happened with that injection pump is causing this. Can a injection pump cause a partial miss? Could there be a piece of debris causing lack of flow on one injector line?
Worth mentioning, blow by seems normal. No serious puffing like a hole in a piston. Oil is clean, coolant is clean. A heavy smoke haze can be seen at night. It’s almost embarrassing to drive. I have not done any compression or leak down test.
Thanks everyone. I am completely besides myself in this one. I wish whatever the hell it is would just show itself and be done with it. So frustrated.
OI82
Now, about a week later this mystery miss began. I’ve tried isolating it, swapping injectors, cracking injector lines. I pulled the valve covers, all rockers where they supposed to be. I even ripped off the entire top of the engine to replace the lifters, as I surmised the old lifters might not like the new Comp 910 springs and possibly a valve wasn’t being allowed to fully open properly. Still nothing. Now just last night I threw in a complete set of different injectors out of a engine that purrs like a cat. STILL misses and now it’s really pronounced. They are stock injectors, the injectors I had in were stage 1 injectors from another reputable performance shop.
I’m clueless. But starting to seriously wonder if whatever happened with that injection pump is causing this. Can a injection pump cause a partial miss? Could there be a piece of debris causing lack of flow on one injector line?
Worth mentioning, blow by seems normal. No serious puffing like a hole in a piston. Oil is clean, coolant is clean. A heavy smoke haze can be seen at night. It’s almost embarrassing to drive. I have not done any compression or leak down test.
Thanks everyone. I am completely besides myself in this one. I wish whatever the hell it is would just show itself and be done with it. So frustrated.
OI82