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Discussion Starter · #1 ·
Cylinder performance test by the dealer reads. #1 97% #2 92% #3 98% #4 111% #5 106% #6 95%.
Also high and low side fuel pressures are good, transfer pump volume good.

Reccomnds all 6 injectors but says 4 for sure 1,2,3,6

2,3,6 were replaced with remans 2500 miles ago so they will warranty.

What are your opinions, on what to replace or where to go from here. these tests were not cheap so hope it was all done correctly.
 

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Replace 4 and 5 for sure, the rest look within spec. The highs on the 2 bad ones will effect the ones next to it in firing order. Need to run the test again after replacement to see how they balance.

Probably an injector return flow test after replacing the 2 would be in order.
 

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Discussion Starter · #3 ·
Now I don't know what to do since the dealer says the opposite. I didn't expect the dealer to give the right info. Is it correct that the high numbers are actually under fueling and the lows are over. They did say that they try to compensate for each other so I can see why it would be hard to know. But if a tech or person has seen and done this fix enough he would know the correct repair to get the #'s back to 100.
 

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The dealersship said what??? :confused013:

If that is really what they told you then all I can say is :doh: :banghead:.


Blasted parts changers don't a thing about what they are working on. The contribution percentages are a calculation. The ECU is calculating how fast the cylinder moves down on each event and comparing that to the over all rpm. The sum of the parts is always less than the total because of parasitic loss and caluclation error, hence, you see the bulk of the numbers under 100%.

Lower percentages mean the piston is moving slower, less fuel than avergae of the others. Higher percentages mean the piston is moving faster, more fuel than the average of the others.

Look at the percent drop as the revs slow and speed with the higher percentage contribution in the firing order. The ECU pulling fuel back trying to maintain rpms. The spacing when you have normal cylinder adjacent is much smaller:

1-97
5-106
3-98
6-95
2-92
4-111

Two the first 4 cylinders are over fueling causing the last 2 to dip low to compensate. The ECU can only pull back so much by design and kinetic energy keeps 1 and 3 high but 6 and 2 show a normal drop.


Knowing that, look at the percentages again. Its obvious 4 and 5 are over fueling, #4 by a lot. #5 is not as far out but too far for balance.

Generally a stock injector patter would be 92-98% for the spread, 1% either side of that is not unusual. That equates to 5-6% variance being a "good" set. Less than that would be an "excellent" well balanced set.

When the outlyers are over 10% off from the average of the 5-6% variance, they are bad.

Thank your public school system physics is no longer required and deductive reasoning is replaced by the lowest common denominator of cognizance. :rolleyes:
 

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Just for clarification, can someone explain how the cylinder contribution test works?
Does the scan tool actually cut out injectors to measure RPM drop, or does the scan tool or ECU just measure the RPM at a very high sampling rate with the injectors firing as they normally would.
If a cylinder was only measuring 25% performance (as happened to a friend of mine) there is major lack of compression such as a hole in a piston, and hence the RPM would drop below the average RPM when the bad cylinder is undergoing its power stroke.

Would an injector kill test help identify injectors that are over fueling? I think during the injector kill test, the dealer also looks for RPM drop...so when killing the injectors that are over fuelling, the scan tool should see the largest RPM drop based off the reading from the crank sensor.....But I might be wrong. Maybe during the cylinder kill test, the ECU measures the amount of extra fuel required to maintain RPM while individually killing injectors.
 

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Discussion Starter · #7 ·
Awesome information when I haven't worked in 95 deg heat all day I will take some time to come up with a proper response or more ?'s. I am glad I held off on the repair while I decided what to do and started this thread here. Thank you we might have avoided a melted piston or two here.
 

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Discussion Starter · #8 ·
I will replace 4&5 on my dime. Leave number one alone but would you let them replace 2,3,6 under waranty if they are willing or just leave them alone? Also how much labor should I be paying on the 2 and if they want to do the other 3 should Dodge pay labor under the parts waranty?

On another note I would like to do something like a fass or airdog. What would be best for a stock truck. Also I would like to spend closer to 500 than 700 and would like to DIY the project. Any recommendations?
Thanks Cerberusiam
 

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I don't understand, why would you have to replace 4 & 5 and they would do 2,3,6 under warranty? If they want to warranty something make them do 4 and 5.

Quite frankly, if they tried to tell me 4 & 5 are good and 2,3,6 are bad I would run not walk away from that shop. If they cannot figure out how to interpret the numbers then they have ZERO business doing naything to the truck except an oil change if you watch them closely.

It is up to you and maybe you don't have another dealer close but I would not trust them. I would drive to the other side of the state to Belle Fourche before those guys would touch my truck. :hehe:

But thats me, I am a butthead about ignorance and stupidity costing me money when the people I have to pay should know better. :)
 

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Discussion Starter · #10 ·
2,3,6 are under parts warranty and the other 3 are originals with 125 k on them. That is the history I have on the the truck about the injectors. I did take it to a diesel shop that works on these years but for some reason they're DRBIII could not communicat with the truck so that is why it went to the dealer, & I hated every minute of it. I also don't know of any other places at this moment and I did not want to drive it . It has been sitting for over a month while I've been trying to get the right info and place to have it fixed. I also posted here in the south Dakota forum to see if anyone new of a place to go. We have no cummins support here for our trucks that I can find, there are other dealers within an hr but its a crap shoot. When you talk to dealers they will always say they have the blah blah blah to fix it right. I told the advisor I would wait for an experienced tech and he didn't even respond to me. Very frustrating situation. That's why I really appreciate your help cause you are my best bet at good information.
 

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Yeah, I know just what you mean. I have gotten totally disgusted with the dealers and just do the work myself if at all possible. Check with the big rig dealers and see if they know of good shops. Cummins Power LLC is in Sioux Falls and may be able to give you a shop reference.

Replacing the injectors is easy with some basic tools and knowledge. #4 is easy to get at and 5 is not bad. If you can find a source for NEW injectors that is the route to go. The crappy Dodge supplied remans are not to be trusted and they won't spring for the good ones. I would replace 4 and 5 imediately and monitor fuel consumption, smoke, etc, on the others. With good cleab fuel you might get a lot of miles yet.

Since you have 3 that are bad or original and 3 remans a complete set of new is the optimal way to go. You could buy a set and find a reputable shop to put them in. They don't need to have all the fancy scanners to just swap injectors unless they want to perform tests.

How many miles total and what year truck? I didn't see that in signature or posts.
 

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Discussion Starter · #12 ·
125,000 total miles on an 05. I just ordered the Mopar severe duty filtration kit, there is a huge write up on here about it and seam s the way to go for the money and ease of installation. http://www.cumminsforum.com/forum/3...y-fellas-its-christmas-look-what-i-found.html. I do fuel at the same small truck stop for the last 2.5 years. Also the first shop I took it to can sell me reman injectors from Bosch for 375 each and I'm sure they would install them if I ask nice, he was reluctant since he could not connect to do any work to the truck. Also he said new were not available anymore and looked at me like I was stupid when I asked for them. I am really good with repairing vehicles but I was an Audi tech, quit in 2003 but I am lost at times without wiring diagrams and a scanner lol. I have just never worked on diesel engines except for maintenance. I see there is a special tool for removal and install of the injector, is that not really needed? Also the valve adjustment when complete scares me a bit, I do have a feeler gauge but am afraid to use it lol.
 

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That is because he doesn't really know what is going on with the injector thing. New are available. I can put you on to 2 sources of new for about that same price.

The part number that the injectors are sold under is a reman number and has been for several years. Bosch was seeding the market to get the old injectors back because they could not keep up with demand.

If the supplier cannnot veirfy they are new inejectors I would not go there unless they would just be changing them. I would buy elsewhere and have them professionally installed if you don't feel comfortable. If you can do the actua mechanical work on an Audi, you won't have a problem. There should be a good write up in the tech section on injector changing. If not I have a PDF I can email you.

The severe duty thing is worth it for the fuel heater and you can use that in the winter. I would definitely have a gauge at the CP-3 watching pressure if you have the OE lift pump and go down to finer filtration.
 

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Discussion Starter · #14 ·
UPDATE: I put # 4&5 in myself a few days ago. Truck runs and starts good, I dont smell the sweet smell from the exhaust anymore and it doesnt haze white under light pedal pressure. The bad: Under light to medium acceleration it hazes black and also when you step on it even a little it puffs black. I have checked the air filter, turbo, and intercooler which I think has been updated since it is metal and not plastic, also checked the piping for leaks, fuel filter has 1500miles on it. I guess it could be the heater grid gasket since it has been apart and back together and reused. I am going to pull the valve cover and check the valve adjustment today just to make sure. Should I even worry about it?

I plan on using the mopar severe duty system with a cat filter or similar, is that what you meant by only good for the heater
 

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If you are compeltely stock, you should not get any smoke at all at normal throttle. The only time you should see a puff of black is hammering the throttle right after crusing at a steady throttle for quite a while. The soot will build in the CAT and muffler then get pushed out when you nail it but it should clear almost immediately.

Do you still have a CAT or is that gone?


You have the normal sysmptoms of reman injectors. They are working ok for the most part, but, fueling too much due to wear.


Thats my best internet diagnosis. :hehe:
 
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