Can’t find miss, please help!

[OldIron82]

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

 

[Big Bart]

Some thoughts.

1) Check your timing.
2) Check the temperature sensor to see if it is powering up the cold IP advance when it happens. (Or unplug it so it does not work. ) Maybe it is sticking or coming on at random. Thus the intermittent clatter.
3) Run a compression test to see if you have reason for a miss. (You May have 2 separate issues.)
4) If all checks out I would send the pump back, discuss all the tests you did. Say it looks like a IP isssue. One low cylinder is not going to advance your pump timing. The pump is fairly complex, perhaps a part went bad or became loose.

Take a couple pics and post, let us know how things are turning out.

 

[The_Josh_Bear]

What did the IP builder say when you called him/her on that trip where the timing got all crazy?

Also to clarify:
1. You had a crazy timing-related "event" and kept driving it to your destination.
2. The next day your IP was normal again but at some point it developed a partial miss on one cylinder.
The way I read it kinda sounds like you're saying a miss sounds like crazy advanced timing which is certainly not the case. So I figure I read it wrong.

 

[OldIron82]

Timing is right on the money, a very reputable member here timed it for me perfectly.
Cold advance has been unhooked for quite some time now.
Yes I kept driving to my destination that night.
The next day it ran like nothing happened, and within a few days this partial miss appeared.

 

[Big Bart]

I would run a compression test, if all the cylinders are within 20% of each other, it would suggest an injector or the IP has an issue.

If compression is good, when it has the miss happening, start to crack injector lines (Rag over it so diesel does not shoot at you.) till you find the cylinder that least affects the RPM, that will be the cylinder with an issue. Then swap an injector from a different cylinder into that one. (Replace the copper crush seals.) If the miss follows it is the injector.

If not you should send your IP back for testing. Begs the question why the clatter came, generally that is going to be an injection issue. (Timing moved or advance came on, or there is an issue with the pump or the connections to and from.)

Post some pics and let us know how things are going.

 

[OldIron82]

What is the best compression tester to use? I’ve read some nightmarish reviews about the most popular one on Amazon, saying it doesn’t have a check valve to hold pressure, or something like that.
I can already tell you the second cylinder from the front on the driver side is the culprit. I have cracked lines multiple times and always found that one too give a subtle change, the other 7 result in a dead miss. I have swapped the injectors, nothing changed.

I had a valve job done before assembling the engine. I have no idea why anything could be valve related. I believe I’m correct in saying mechanical problems don’t heal, they are either screwed up or not. What with a valve could come and go and vary in intensity? If a injector is popping with more fuel or less fuel at different times, I could see that doing this.
Thank you for the replies gentlemen

 

[Big Bart]

Some thoughts, sorry in advance for the long message, these questions are not simple answers.


1) What is a good compression tester?

a) If you want great then a Snap On, you can buy them used on eBay and Offerup.
b) I have had good luck with the OTC one on Amazon. I bought the gauge and then the fitting for ford IDI's. (I bought a kit of fittings, but do not recall what brand.) Most of the connectors between the gauge and the glow plug fitting are universal, sort of like an air hose. (But unlike compressor hoses, I have not seen different types.) Later I ended up finding a deal on a Snap On gauge and bought that.
c) If on a budget, some have had luck with the Harbor Freight gauge, some say you have to cut the glow plug adapter as it does not taper like a real glow plug. (But all you need is the threads up to the fitting. The rest is not relevant, should only change the compression by 25 PSI or less. (More volume, less compression.) Some say theirs worked, so guessing something changed at some point.
d) A gauge should have a Shrader valve in the tip of the hose, that way air cannot leave the compression tester and you can see the total pressure for say 5 compression strokes. At 300-450 PSI rushing the gauge in an instant, that can damage the Shrader valve. Also, crud, oil, soot, can shoot up the line and make the Shrader valve stick slightly open. Usually not an issue, but can happen, so folks should not get too upset. Flip side is gauge manufactures should send a couple of spares.

2) Ok maybe you posted the work prior but not aware this was a valve job, IP, and injectors. So you could have a valve issue, a head gasket issue, or now with higher compression a piston or ring issue.

a) A compression test will confirm if there is an issue. (If swapping injectors did not make a difference, then it is pointing to a IP (Fuel related) or low compression issue.) If there was a valve or seat issue this might of been part of the clattering your heard. You where there and if you have a IDI you know what diesel clattering sounds like. But lets not assume anything yet.
b) Anytime you have mechanical work done, in this case machining, their is a slim chance the work is not well done (They used to say, never buy a car made on Monday.), a part fails (New or used.), or under full compression something else ready to fail does. (Glow plug, ring, piston, etc.)
c) IT could be something related to the valve job, perhaps not. It could also be related such as a bad lifter or bent push rod tube. To your point maybe it comes and goes as it is holding oil pressure then not or maybe a bent push rod spins and at some points does not open the valve as much.

3) If you have bad compression you will need to do a leak down test. This will confirm where your leak is. A valve, head gasket/cracked head (Radiator bubbles or oil bubbles.), or piston/ring. (Blow by from the oil fill.) Keep in mind it could just be a bad lifter.

If you do not have a leak down set (One for a gasser works, should have the same fitting.) you can try to use your glow plug compression adaptor with a rubber tipped air gun. (Start at 25 or so PSI and go higher.) Then you should hear air in the exhaust pipe, intake manifold, crankcase (Via oil filler.), or a radiator bubbling. You will have to hold the crank at TDC on the #4 piston while you do the leak down. The air pressure will try to turn the crank. Best way to do that is to pull the valve cover and see when the valves are both closed. Also a good time to try adjusting that cylinders valves in case a bad lifter or somehow the clearance changed. (Valve top or rocker arm wore down a little VS a bad valve.) You are looking for a good strong sound of air and more so say in one of the areas. A little trickle past a valve or rings would not suggest a need to pull the head. So think about does my intake, exhaust, and crankcase all sound about the same, if so that would not suggest one is worse than the other. However you hear a rush of air from the exhaust but not the intake, well you know the exhaust valve is not working correctly. (Not closing, bad seat, burned or bent valve.)

4) If you do not have bad compression, send the IP back and have them re-work it, it would point to there is a problem with the pressure or volume in that outlet of the IP.

It all goes back to no repair is 100% guaranteed to work or last. If you have done this as long as I have, you have seen it all -

a) Bad parts out of the box.
b) New parts fail within days or weeks.
c) A gasket was damaged when you replaced a part.
d) A new or newer hose is not sealing after you put it on and clamp it.
e) A part that works almost good enough, but causes intermittent issues.

I help my friends nephew from time to time. He always says "that part is new, I replaced that recently". I have to now qualify him carefully, sometimes he thinks putting a part in 3 years ago means "it is new". So now I ask, how long ago, if he says more than 6 months, to me the part is suspect.

It's just part of working on vehicles, if it was easy there would not be thousands of repair shops in your state charging you +$100 an hour.

Let us know how it goes.

 

[OldIron82]

Wow thank you for all of that information!
When I replaced the lifters, I checked all the pushrods on a flat table, all rolled perfectly. No bends.
How can these valves be adjusted? I thought hydraulic lifters took up any lash no matter what?

Trust me, I am well versed in junk new parts out of the box! lol.
I’ll try to get a video of the truck running so you can hear the miss.

Thanks again, I have a lot to get started on.