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

That is great news for you! That is the spirit of MOST ALL of these forums. We are here to help each other in any way we are comfortable.

My trans is not ready for the injectors, so I thought I would put them to good use... Tyler is good people & that is what our community is all about.

 

Ed

Edited December 4, 201410 yr by Yankneck696

This forum is unique... I don't see any members on CF willing to trust someone with a set of injectors. A big thanks to everyone here who has contributed to this forum and this thread. I have learned more here than I have anywhere else! If anyone is in need of a compression test don't be afraid to ask. I will loan it out to anyone in need. It'll probably just collect dust for the next couple years.

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!!! 

and this is why this place is so awesome!

I swapped ED's injectors in today...A big thank you to him once again! But my problem persists as there was almost no change in the sound. If anything the larger injectors may have amplified the problem a bit.

OK, you changed injectors, you did a compression check. You repaired your cross over tubes. Think about what else is in the fuel system............

At least he tole me that my injectors rock....

 

Ed

 

Compression test was good.

 

Injectors are not the cause.

 

Ok. Back up a second. Thinking out loud here. Now diesel engine ignites fuel by heat of compression (autoignition temperature). Fuel has to be sprayed in time by the injection pump and injector. If there was a high pressure leak it could cause the injector to fire late or not at all. But most leaks occur inside the head. If it was a pissy injector Ed's injectors just ruled that out. I know there is other things like delivery valves on the VP44 injection pump. Crossover tubes I think you said you replace one or all.

I replaced all 6 with a drilled out set... That didn't change anything, so I stuck the originals back in. ( I had bought 2 NEW ones and left one of the new ones in the #1 cylinder when I swapped back to the originals) I guess I can go swap out the 1 new one I have left with each of the 5 old ones one at a time and see if it makes a difference, but I doubt it will. 

At least he tole me that my injectors rock....

 

Ed

I would like to see what they would do to your stock transmission 

OK, you changed injectors, you did a compression check. You repaired your cross over tubes. Think about what else is in the fuel system............

going to the edge of the gangplank here. 

answer?  Air.   Air is the answer to 'what else is in the fuel system'..

 

You got a roving  miss correct?

 

And  before  you all jump me  for  'he's got good  pressure'....   that  air bubble will not lessen  the  pressure  one bit.  it'll  compress down to 18 psi just  as  the fuel is  on both sides of it.  Pressure gauge  wouldn't  even notice.

 

Check your fass for any  seepage,  and  the filters too.   One  miniscule  pinhole in the  suction side filter..  (I MEAN  tiny)  is  all it takes.    I've seen  rock chipped filters  wreak havoc.

Seal going bad in the fass may let air  through the motor if the motor is  pinholed too..

I'd get some  clear  hose  to run from the  filter to the vp... and  see if  there are bubbles.   loop it up and  you'll know  immediately. 

Don't keep it  on  the truck though,  it's  pretty flimsy stuff.

Edited December 10, 201410 yr by rancherman

I thought he was hinting at my VP.... If it was lack of air I would think there would be noticeable black smoke. 

He has 2 cylinders with lower temps, so I think it might be 1 of the 3 plungers in the rotor head. Either that or a DV or2.

 

Ed

I thought he was hinting at my VP.... If it was lack of air I would think there would be noticeable black smoke. 

 

no... the air I am talking about is  in the fuel... 

 

lol..  very possible that is what  tom was hinting at!   'my way'  is  cheaper to fix!!!    (if that is what it is!)

the amount I'm talking about  is  small.   in a  3/8's hose,   this amount would be  similar to a  little  white (foam)  stripe.  maybe  1/32 wide at the top of the hose..

Edited December 10, 201410 yr by rancherman

Do you have exhoust brake? If not then go to blue chip site and read all this

http://m.bluechipdiesel.com/site/vp44_diagnostics.html?imz_s=1scguk7n8bmkl247o3ocra7161

It will help you diagnose vp better and he's got other tricks to check sensors etc.

reason I asked about exhoust break is when I changed my injectors I hooked vacum lines backwards and truck had eb on all the time that was right after my injector change freked me out I thought my new injectors were f up. But you know s happens.

 

 

I see what you are saying now! Filter is not an issue as I only have the fass 95 with no filters (Using only the stock filter) I will get a piece of clear line and give that a go before I yank the VP off. 

Do you have exhoust brake? If not then go to blue chip site and read all this

http://m.bluechipdiesel.com/site/vp44_diagnostics.html?imz_s=1scguk7n8bmkl247o3ocra7161

It will help you diagnose vp better and he's got other tricks to check sensors etc.

reason I asked about exhoust break is when I changed my injectors I hooked vacum lines backwards and truck had eb on all the time that was right after my injector change freked me out I thought my new injectors were f up. But you know s happens.

Good call. I think I will try the "Hot Wire" method to see if the engine idles smooth when there aren't any inputs from the rest of the truck 

I see what you are saying now! Filter is not an issue as I only have the fass 95 with no filters (Using only the stock filter) I will get a piece of clear line and give that a go before I yank the VP off. 

 

Ok,  I missed the  fass 95.  (update yer  sig man!!)  LOL

 

Only reason I mentioned  air in the line is:   Lots of   engines  over the years   suffer  eventually  from  it.   Fuel lines, seals,  push connectors... all  get tired.    symptoms    can  range from  miss,  all the way up to   not running, loss of prime..

Granted,   the  source of  air  should be  between the tank... up to and including the fass.

 

You've  pretty much eliminated   the  'moderate'  cost  items..  and  venturing on the  'next level'.;       I just   wanted  to throw this out there  before  taking the  plunge,  and eliminating   a possible   5 dollar 'fix'.  

 

^ rethinking the  plastic hose trick^       instead of    putting it  back to the  VP   just   route it  back to  a bucket on the ground,   choke it  down  a little  so it  flows  a little  slower  ( wide open fass  probably  will  shoot  pretty fast )

Loop it  up  and over the fender,  then back  down to the  catch pan.  

If nothing  else,   you'll eliminate  this possibility  for  only a  couple buck  'test'.

I'm not exactly willing to say the VP44 is the cause yet. But I'm trying to think on single cylinder logic. Because if the VP44 typically is dead or dying then all cylinders are typically affected. But at what point does it turn independent is right after the rotor of the VP44 and entering the DV (Delivery Valves) then its separated system for each cylinder. I'm still trying to think it out as a single cylinder theory (intake air, compress, fuel is injected, BOOM!, exhaust and repeat.) This is why I can't quite say VP44 yet. Because 5 other cylinders are still working. So with compression in the 400 PSI realm, new injectors and drilled out crossover tubes I'm really starting to scratch my head.

 

I'm thinking alone the lines of JL Welding and his problems. His wouldn't miss right away it took time for the piston to heat up and the crack would open up and allow compression to fade. Then the misfire would start. So what conditions do you have to have to get the miss fire?

Cold, hot, anywhere in-between... Doesn't really matter engine temperature or exhaust temperature wise.