Alright guys I am experiencing a miss at all RPMs. It is pretty noticeable near the engine with a knock, but is extremely noticeable at the exhaust. It is easy to feel that the exhaust is "puffing" per say. Now I just replaced the injectors with a new set of 125hp sacs, but the miss was prevalent before the injector swap. The swap did not make a difference. Everything sounds the exact same as before the swap. I have fuel squirting out of each connection at the cross over tubes while running.

MoparMan and I spoke on the phone earlier and have decided to take a systematic approach to resolving this issue.

Ruled out: 1. Injection pump: Always supplied good pressure, less that 10K miles and miss seems to only be in one cylinder. 2. Injectors: Swap made no difference.

Possibilities (Almost endless): Burnt/ broken valve, broken piston or piston rings, clogged cross over tube, valves way out of adjustment

 

I should receive the truck Friday from being painted and I can start diagnostics. 

The plan: 1: Pull valve cover and quickly check valve lash - just make sure somewhat close to spec. 2. Use an infrared heat gun on the exhaust manifold right were it come out of the head to try and narrow down which cylinder is missing. If that does work I will pull the cross over tube and replace it (I already have 1 new one that will ship out Monday). If that does not fix the issue I will do a compression test on that cylinder to determine if it is the bottom end or the head.

If the heat gun does not find a "cold" cylinder I will pull all injection lines and cross over tubes, then clean each tube and try to determine if there is debris in one of them. If I can not find debris in any of them I will replace them with the new one, one at a time. If that proves inconclusive I will perform a compression test on all 6 cylinders. 

If any of the cylinders are low on compression I will pull the head and determine what is wrong internally.

 

Any suggestions on the procedure or something else I can do to diagnose what is wrong with this thing??

Edited October 26, 201410 yr by TFaoro

id toss in a different pump, its the last thing to be changed...

id toss in a different pump, its the last thing to be changed...

For the cost I wouldn't want to do that. His last IP tested just fine so there is something else going on.

I'd  still  check for air in the fuel.

Edited January 5, 201510 yr by Mopar1973Man
Return to normal size so it can be read.

Great thoughts guys! Sorry I have been away. Let me answer a few things here....

We don't have any Bio around here so that is not an option, but I appreciate the suggestion.

There is not an extra copper in #6, as I made a "special" piece of wire to pull those out (Some of mine didn't stick to the injector when the injectors were pulled)

Mike... Not a bad idea there... Although this is the second set of washers from DAP and they are the same thickness as my first set of injectors from them. I don't think I have the stock ones to compare to either... Could that cause the slight miss though? I wouldn't think a couple millimeters would cause spray to go outside the bowl of the piston. 

Another injection pump is not an option. Too much money and I was told it tested out perfect.

Tom - The valves have been adjusted a couple of times through all of this. No irregularities found there.

Rancherman - I will be testing that as soon as I get the pump put back in. I'm hoping it shows up tomorrow! 

If the issue is still there after the pump install, I am leaning towards a valve train issue. Let me know & I will ship out the dial indicator. Also, it may suck, but you may want to pull all of hte pushrods & check them to be straight.

 

Ed

I'd  still  check for air in the fuel.

  Just  being  silly with the tiny print.    Like the  guy  whispering in a  convention hall during a  heated  debate..

Edited January 5, 201510 yr by rancherman

The reason I said to adjust your valves was to have you check for excessive wear, excessive adjustment, lack of valve movement, etc. If you notice one adjuster different than the others it will tell you where to concentrate your efforts.

I am going to pull all of the pushrods now. We'll see if ant are bent. I will also check those things Tom. Thank you

i know you have done a compression test. but i still think there is a cracked/broken ring.

Pushrods have been checked and all 12 are straight. The adjustment on all of the exhaust rockers are very close, and the adjustment on all of the intake rockers are very close. 

 

i know you have done a compression test. but i still think there is a cracked/broken ring.

If there was a broken ring I believe it would have shown up on compression or leakdown test. 10 psi difference does not point towards a ring. 

The pump didn't show up today  So tomorrow I should be able to test the fuel with a clear line. I'm hoping it's something as simple as air in the fuel!

Without rereading the last 10 or so pages, did you narrow this down to one cylinder?

Pushrods have been checked and all 12 are straight. The adjustment on all of the exhaust rockers are very close, and the adjustment on all of the intake rockers are very close. 

 

Well, you sure shot the crap out of my ideas........

When you say miss at all rpm that means even before it starts to boost so you can rule out turbo and boost leaks, and if engine checks out good the only thing left is really fuel. And if injectors is not the cause how good is the place that tested vp. Other than that maybe valves or valve seats or even head gasket. And maybe when you did tests it's cold and doesn't leak, and if it gets to higher temps is when it happens. Man I really want to know what it is now. It's bugging me.

Edited January 6, 201510 yr by Dieselfuture

Without rereading the last 10 or so pages, did you narrow this down to one cylinder?

No sir... Can not seem to narrow it down to a single cylinder

 

Well, you sure shot the crap out of my ideas........

They have all been good ideas! I'm about out myself....

 

When you say miss at all rpm that means even before it starts to boost so you can rule out turbo and boost leaks, and if engine checks out good the only thing left is really fuel. And if injectors is not the cause how good is the place that tested vp. Other than that maybe valves or valve seats or even head gasket. And maybe when you did tests it's cold and doesn't leak, and if it gets to higher temps is when it happens. Man I really want to know what it is now. It's bugging me.

Industrial Injection is the one who tested it on their Bosch test bench, so I think they did a good job. As for temperature it doesn't really matter how hot the EGTs are or the engine temp ... it has that slight miss either way. Hopefully a piece of clear line will tell me there is air in the line. 

I'm wondering if you can just monitor the overflow coming out of the vp with a clear hose..

2 questions.

where are you 'hearing' this miss? in cab, or at the rear of truck, by the tailpipe? You feeling a stumble too? Does this miss disappear when engine is under load? (you only hear it when engine is freewheeling?)

Then, what kinda shape is your exhaust system in? Turbo- through- tailpipe?

Yesterday, I fired up my ol Massey with a 540 perkins, and right where the 'y' brings both exhaust banks together, it's a little loose. Simple slip fit, just needs the clamp tightened.

Standing back 20 feet while I was closing a gate, I could hear a sporadic pop-miss, ever so slight.

I says to myself.. hmmm, I wonder if that dude is mixing air and getting a pop... or he has a little oil leakage on the turbine side, causing a little pop-miss..

There is a slight chance of a broken ring, that when 'static' it will seal up under pressure. And it's fooling you.

Great questions rancherman. It can be heard at the engine (Hood open or closed), which gives a knock and shakes the truck a bit. It can be heard at the exhaust as well. The exhaust is a Magnaflow 4 inch turbo back with a muffler. All of the connections in the exhaust system are tight and not leaking (Verified this morning). 

 

As for when it misses.... freewheeling is when it is most noticeable. Once under boost you can't hear anything over the turbo so if it is missing under boost I have no idea. I'll see if I can test a bit more today and give you an accurate description. I haven't driven it in close to a month.

I was afraid you'd say that! *exhaust system is good* And the fact you can feel the engine drop a cylinder.

Hey, I'm too lazy to go back and read. Did you use a leak down tester, or just a compression tester? Also, to the best you can remember, did this come on all at once?

have you noticed a increase in soot build up in the tail pipe? what is your oil consumption doing?

Both compression & leakdown were within specs.

 

Ed

Zero oil consumption in 5,000 miles.

Seemed gradual to me but I can't remember exactly. 

does this happen from cold or after it gets to temp?