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

heres one with our adapter

http://m.harborfreight.com/14-piece-diesel-compression-tester-set-46800.html

Edited November 21, 201410 yr by CUMMINSDIESELPWR

heres one with our adapter

http://m.harborfreight.com/14-piece-diesel-compression-tester-set-46800.html

It says it's in there... But I can't tell which one. I've got the gauge with me and the slug is supposed to come in Monday. Tuesday night I will know the condition of the internals! On a side note I put the original crossover tubes back in tonight and it has lessened how harsh the motor sounded. Before when the grids would kick in it would make the motor lope a and now it's smooth. 

Ok guys I got #1 and #4 compression tested. #1 had right around 440 psi and #4 had somewhere around 430 psi and I plan to test all of them tomorrow. But from the looks of it number 1 is ok. I am also going to leak down test each cylinder but I'm not sure how to hold the engine still without a baring tool? Any ideas??

Simple... It's a 5 speed transmission. Just stick in 5h gear and set the parking brake. An automatic I would get creative with a wedge or strap on the front pulley.

 

Make sure you report all your compression numbers.

 DUH That was dumb of me. I will get that completed tomorrow and report back!

 DUH That was dumb of me. I will get that completed tomorrow and report back!

 

It's all good we all make dumb mistakes. But at leas its a easy fix to the problem.

Heading out this morning to compression test all 6 and do a leak down test on all 6!

Keep the  zippers and buttons   off the  fresh paint man!!

Heading out this morning to compression test all 6 and do a leak down test on all 6!

I was going to tell you to test all six. Testing one or two doesn't mean much. The main thing with the comression readings is to have them within 10% of each other.

Results: I cranked the engine over for 4 seconds with a timer for each cylinder

1- 410 

2-415

3-400

4-410

5-400

6-410

 

Compression looks good for all of them. 

As for the leak down I have one cylinder that has a very small leak coming out of the intake when at 100psi. It also sounds like it is gurgling a bit so I think there is oil leaking down on it. 

 

None of this points to a problem that would cause a miss like it has though. I may look at some new valve seals but I'll have to see. Any ideas guys?

Edited November 26, 201410 yr by TFaoro

Well you confirmed the cylinder health is good now you'll have to move on to the injectors. Have them pop tested.

 

TFaoro was that compression test supplied by Harbor Freight have all the right fittings for testing? If so I'm going to look into buying a compression gauge myself. I work on enough diesel locally I really could use it.

I guess I'll send the injectors out during Christmas. I may do the VP at the same time... No the kit did not come with the slug. Here is where I got my slug https://www.tooldiscounter.com/ItemDisplay.cfm?lookup=STATU-15-27

I'm going to have to bookmark this and get these bits and piece myself.

The  cylinder that  is  sizzling/gurgling is the one  I'd  expect  that is  not firing  quite right.   It's probably  'wet',  and  that 's what you're hearing.    Wet from  fuel, and not  oil.

 

Now,   to zero in on why it's  coming  back through  the  valve,  might  be  just  a blob of  wet  crud  that  should  hammer out  when  it  (cylinder)  is firing  hot again...       It  doesn't take much of a  crumb to hold a valve  off  it's seat.

 

Your  compression numbers  are  nice and even...   I've sure seen    higher spreads  and   we  put  a  lot more hours  on it before  a rebuild!

Safe to say  you've eliminated several  possibilities today!

I guess I'll send the injectors out during Christmas. I may do the VP at the same time... No the kit did not come with the slug. Here is where I got my slug https://www.tooldiscounter.com/ItemDisplay.cfm?lookup=STATU-15-27

I don't know if this will help at all, but I had a miss that went on for few years, finally listened to all smart people on this site and changed injectors and immediately miss was gone. But my truck only did it when pulling trailer and putting load on it. But a year or so went by and I just experienced same miss last time pulling. Really pissing me off. So yeah it's hard to believe new injectors can be bad but I don't see another reasonable explanation. I've done almost all tests to eliminate sensor and vp problems and it lead to replacing injectors. And now I just haven't had time to call dap and see if they can test their rebuilt 60hp injectors correct problems if any and see if it does it this time. I hope they do as they have good reputation. Good luck with your problem, I feel your pain.

I don't know if this will help at all, but I had a miss that went on for few years, finally listened to all smart people on this site and changed injectors and immediately miss was gone. But my truck only did it when pulling trailer and putting load on it. But a year or so went by and I just experienced same miss last time pulling. Really pissing me off. So yeah it's hard to believe new injectors can be bad but I don't see another reasonable explanation. I've done almost all tests to eliminate sensor and vp problems and it lead to replacing injectors. And now I just haven't had time to call dap and see if they can test their rebuilt 60hp injectors correct problems if any and see if it does it this time. I hope they do as they have good reputation. Good luck with your problem, I feel your pain.

P.s. I would wait on vp, no reason to change it if it's still kicking. I almost changed mine tracing my problem and glad that I didn't, never know new one can have a bad computer in a year or sooner.

I would opt for the injectors to be tested. If cylinder health is good then its a fuel issue... There is only 2 things needed for diesel to fire. Compression and fuel. So if the compression is correct then its going to be a fuel issue. I still think injector pop testing is in order. It might be just a poor tuned injector maybe or something sticking? Won't know till you do some more testing.

Thanks for the tips guys! Sorry I have been away for the holiday. If I do anything with the VP it will be sent to Industrial Injection to be tested. I will not just replace it for the heck of it. I will likely hold out on the VP and send the injectors in to be tested over Christmas. I'm not sure why changing from one hole to the other didn't make a difference though?? I took it to a guy who owned a diesel shop for years and he said it sounds like an injection knock. On a positive note I drove back to school today and netted 23.6 mpg (Distance was calculated using a GPS)  It was about 30 miles at 65mph 50 miles at 77mph and the rest at 70. That is my best mileage to date.. Even better than the 90hp injectors! Oh and forgot to mention the first 50 miles I had a HARD head wind to fight.

I still don't feel the VP44 has anything to do with the issue I still think at this point your injectors are more of a cause.

One VERY generous member on this site (If he want's to come forward I'll let him do that himself) has offered to send me a NEW set of injectors that he has yet to install. I should get around to installing them this weekend or early in the week to find out if the injectors are the cause! Once I find out I'll send him his injectors back. This way I don't have any down time and I'll know where to look next. Thanks again to that member!!!