Dodge Cummins Diesel Forum banner
  • Hey everyone! Enter your ride HERE to be a part of October's Cummins of the Month Challenge!
1 - 6 of 6 Posts

·
Registered
Joined
·
200 Posts
Discussion Starter · #1 · (Edited)
Just checked my lash, most were at the max or over the allowable.

Also took the resistance of the injector coils. With the injector nut keeper system all nicely turned up, I didn't want to remove them etc. So I unplugged the connectors at the head.

All the readings were 0.4ohms.

Was thinking that why couldn't you just unplug the connectors and use the connector pins, if you know the corresponding pins of course.

Any reason not to do this?

Seems that above 1 ohm is bad and a zero ohm reading is bad?

I thought it was odd that all 6 were 0.4 ohms.
 

·
Registered
Joined
·
1,959 Posts
I check all at the plug, this is a better way to do it. the solenoid is not built like most people think it is. it's not a coil but a quarts crystal with a plating for conductivity, when a voltage spike occurs it warps the crystal by piezoelectric effect opening the orifice for nozzle flow. the parts connected to the crystal have clearances in the single digit micron area, the stock fuel filter was a 10 micron filter. dirt would bind the parts causing excess strain on the crystal causing the crystal to crack. depending on where the crystal cracked will determine the end ohm result. I have personally seen it from 1.2 ohms to 38 ohms. cummins mechanics tell me they have seen it as high as a open reading. a mechanical failure or over tightening the wire nuts can also crack the crystal. we got lots and lots of experience on our early 03's with the dirt. the first injectors and software the injectors would vary in ohm's by a small amount say +or- 0.15 ohms. so you would enter the serial number of the injector that had the ohm value encoded into the number and assign it to a particular cylinder. changes were made to the software so that the ecm could self detect the value and correct for it. on three different occasions where the crystal failed at 2 ohms or less, the truck backfired one time and went into limp mode. you can kill the engine and then restart, the ecm will try to adjust and if you do not load it heavy or go high rpm there will be no issues. I have drove around for three weeks waiting for a new one to come in. with this one 03 that we received in 02 we had more injector problems than nearly anyone here will have in there lifetime before we melted the engine at 14,000 miles. all of the injectors were sticking but as soon as we entered the dealer yard no problem, the mechanic had never worked on a cr and the only thing I knew it was not a pos vp44. 19 out of 20 times the injector would stick closed but the 20th time it would stick partially open when it does since the cr has full time rail pressure it sprays fuel full time, the engine fights itself, egt skyrockets, very heavy black smoke, and mpg converts to gpm in a very short time the engine sezes up. if it happens kill the engine as fast as possible wait 30 seconds and restart. nearly every time it will clear itself. we kept telling this dumb broad with Chrysler warranty that they needed to change the injectors now and not when the code is thrown, she refused and I said do you want me to drive it here with a stuck open injector for you to see witch one it is or melt the engine trying to get here, she said (if that is what it takes). next day it stuck we got about three miles before the engine melted. they put the old head back on with the two remaining injectors that not still had not been changed out and one of them was intermittently sticking shut a hour after we left.
 

·
Registered
Joined
·
1,959 Posts
here is a paste from Brian post
1. Some very interesting HPCR Injector Facts



High Pressure Common Rail Injectors

The clearance between the injector needle and the guidance is 2µm.

2µm ? =.0000787 or rounded UP 8/10,000ths of an inch. A VERY tight tolerance. By design, we need this needle to open & close (lift & lower) with the alignment as correctly as possible, to insure the male conical tip of the needle correctly aligns with the female conical seat, to insure proper opening & closing events.


At 2000 rpm this opening & closing event is completed 2000 times every minute, including the pilot and main injection events. At 3000 rpm, 3000 times every minute & @ 4000 rpm this opening & closing event occurs 4000 times EVERY MINUTE.



Now lets take a look at the pressures this needle tip is exposed to. Oem values are up to 23,500 psi. Some tuning enhancements run these pressures up even higher ? Wow. Now we have fuel exiting the nozzle holes at OVER 23000 psi under full power demands. The needle is moving up & down vertically & RAPIDLY ( up to 4000 times per minute) opening and closing, injecting a precise amount of fuel with each & every event.



Lets take a better look at these nozzle holes. It makes sense that they NEED to be in a uniform pattern, and with a uniform size as to provide equal pressure against the needle, within the guidance, to insure the needle is allowed to stay centered. If the nozzle hole pattern/placement is incorrect, or if even ONE SINGLE HOLE is not PERFECTLY sized and matched to the others, these mis matched internal pressures will force the needle off center causing premature wear to the guidance.



One single hole in the nozzle, not in the EXACT proper placement, or of the EXACT proper size, IDENTICALLY matching the others, will accelerate the demise of the guidance, needle and the preciseness of the event. While the injector will "work" with these eccentricities, it WILL have an adverse effect on the injection quantities and the overall life expectancy of the injector.If the conical tip of the needle is not allowed perfect alignment with the female conical seat, we can NOT have a crisp/clean event as the original design intended.



If all these pieces of the puzzle are not exactly correct, it will accelerate tribological wear, because the needle has to slide into the seat before it fits perfectly! Does it seem like the life span of current after market modified injectors is NOT as good as the originals ? One small change in design alters the whole make up or function of the system. For every action, there is a reaction. In our examinations of the "Various Manufacturers" offerings, we are not finding small changes. We are finding LARGE changes that radically effect injector performance and life. We understand WHY our those manufacturers performance injectors deteriorate rapidly. It's also easy to understand why high horsepower CR motors are frequently experiencing injector related engine failures.
the point is your truck needs better filtering, carl
 

·
Premium Member
Joined
·
15,609 Posts
If you are at .4 ohms thru the harness the solenoids and solenoids are good. If you would have had a high reading then you start checking solenoids and harness to find the issue. The solenoids are pretty simple, just a coil relay in basis. The one thing that might effect them is heat from use. If you aren't getting random injector codes and a CEL you are good to go.

These aren't piezo injectors so a simple test will tell you if the solenoids are good. What it won't tell you is internal wear that is the usual problems.
 

·
Registered
Joined
·
2,181 Posts
If you are at .4 ohms thru the harness the solenoids and solenoids are good. If you would have had a high reading then you start checking solenoids and harness to find the issue. The solenoids are pretty simple, just a coil relay in basis. The one thing that might effect them is heat from use. If you aren't getting random injector codes and a CEL you are good to go.

These aren't piezo injectors so a simple test will tell you if the solenoids are good. What it won't tell you is internal wear that is the usual problems.
Carl has been piezo confused for a while....
 

·
Registered
Joined
·
200 Posts
Discussion Starter · #6 ·
carl48, thanks for the great info. It is very unfortunate that Dodge nor Cummins spec a proper 2 micron filter from the get go. a water trap spin on and a fine filter would have likely eliminated many issues that people are dealing with. There would have been 2 filters they could have made money on as well...

My issue with the high mileage at 390k miles, is not knowing the injector history etc. The prev owner put 280k miles on it in 4 years hot shotting. He bought it with 182k kms.

Likely I will get a rail cap to isolate the injectors to see if there is an offending party.

Still have to check the flexplate and do the CP3 phasing, but is knocks when cold, and subsides when it warms up. Under load there is standard diesel sounds, but when cruising, there is some knocking.
 
1 - 6 of 6 Posts
Top