Injector failure on my 03 3500

[Kirwin]

I recently returned from a 6300 mile RV trip (GCW of 22K) out to New Mexico. While on the trip, my truck developed an engine noise that sounded like the typical 12 valve clatter but with a deeper tone too it, kind of like a light rod knock "clack" at idle and up to about 1200 RPM. This was most noticeable when starting off from a stop when the engine was under load at near idle such as during clutch engagement before boost was present. A "rough idle" condition that was also occasionally present that was most noticeable in the vibration of the gear shift lever at idle and caused my BD exhaust brake switch to rattle. I pulled the mountain passes in Colorado on I-70 with no problems at about 54 MPH in 5th and there were no high speed indications of a problem. Fuel mileage was down a little between 10-11 MPG which is close to my long term pulling average of 11. 6. Oil level was constant for the trip, and I had just over 10K on this oil change when I got back home and changed the oil. The oil was still clean enough that I could see the "add" print through the oil on the dipstick. I had a 0633 code with is crank position sensor (CPS). After discussing this with my mechanic at the dealer and researching on the TDR, I thought it most likely an injector. I talked to Mark at TST to get his opinion and he gave me a few other things to look at but everthing else came up good. After removing the TST PMCR I took the truck in on Tuesday. My mechanic checked the CPS and it measured out OK. The injector kill test was perfromed and when cylinder # 2 was "turned off" the engine noise/vibration was unchanged. Killing any other cylinder made the engine shake badly as a 6 cylinder doesn't run well on 4 cylinders. A new injector was ordered which the parts system changed to a reman injector as there are no new injectors any more according to Dodge for the 03-04. 5 trucks I guess. A close inspection of the injector showed no abnormal indications. It looked just like any other used injector. The new injector was installed Thursday and the truck runs like new again. I had the valves adjusted while he was in there and he only had to move a couple of them. Cost was $853. 00 to Dodge. I paid $90 for them to adjust the valves. As a side note my mechanic said that I had the cleanest engine internals that he has seen in a truck with 50K miles on it. Made me feel good any way. Ken Irwin

 

[Mobius1]

ITs a good thing that it was caught before something really bad happened. Glad she's running strong for you

 

[betterthanstock]

Sounds like it a dead coil. It stuck closed, so no damage!

 

[Kirwin]

I don't really know how it failed

beterthanstock I guess maybe, but I don't think it was only running on 5 cylinders under load. After all, I came all the way across the country with it sometimes clacking at idle and sometimes not. I think it just didn't spray like it should untill it was passing a significant amount of fuel. Ken Irwin

 

[betterthanstock]

beterthanstock I guess maybe, but I don't think it was only running on 5 cylinders under load. After all, I came all the way across the country with it sometimes clacking at idle and sometimes not. I think it just didn't spray like it should untill it was passing a significant amount of fuel. Ken Irwin

Well then, it probably had a slow shuttle (the device that turns fuel off/on).

That would make it too slow to accurately follow the pilot injection rapid on/off/on cycle, which is the cause of 99% of 3rd gen injector clatter.



But after reading your post more carefully, I think it was not opening at all, or barely, at idle, when fuel pressure is lowest. So it was probably still opening some at higher pressure. I'm sure they'll rebuild it and put it in somebody else's truck.



The claim that they don't have any new injectors for our trucks is a bit worrisome. You can't rebuild old stock forever.

 

[MickeyMiller]

Betterthanstock,

That bug is really irritating... I now have smudges all over the left side of my screen... .

 

[Kirwin]

That's what I'm thinking

It obviously worked at higher loads otherwise I couldn't have pulled the Rockies at 54 MPH. I know these trucks are power houses but a 6 cylinder running on 5 cylinders is not a powerful engine. I'm just glad it didn't fail open! Ken Irwin

 

[rbattelle]

Yikes, that was a close one. Seems like they frequently fail in the open position.



I like BTS's explanation of a "slow shuttle". I hadn't heard that one before, but it would make sense.



One question is whether an injector might stick closed at low fuel pressure, then open when the pressure builds. Fuel pressure is used to help open the injectors, so the only thing really forcing the needle against the seat is the spring pressure (I think).



Could it be contamination of the little (tiny) check ball where the arrow is pointing in the photo?



Honestly, I'm a little unsure exactly what happens when the solenoid actuates the injector. I mean, what parts move and what, exactly, forces the needle up. I thought the solenoid lifted the entire needle up toward the top of the injector, but looking closer I'm not sure anymore.



Ken, are you running just the stock filter and lift pump?



Ryan

 

[Kirwin]

Stock except for the TST PMCR

I am still on my stock original lift pump. This is the first ever warranty claim on any of my Cummins powered Dodges and I've had 4 of them. I think, and I'm emphasizing here this is my opinion, the pressure to open the valve has to act on the piston to overcome the spring pressure. Possibily at low loads the injector gets a little sluggish and the valve sometimes doesn't actually ever get open far enough to flow fuel with enough pressure to effectively atomize the short duration fuel flow. Thus the combustion event is delayed as the fuel just sort of drips into the hot combustion chamber and sometime later than designed it ignites. Thats what gave me the clack noise when the cylinder started firing after more fuel and/or boost developed. Otherwise I can't explain why the truck perfromed as it did once up to speed and under load. It certainly wasn't running on 5 cylinders at road speed pulling the RV, I can tell you that without a doubt. Ken Irwin

 

[cerberusiam]

Could it be contamination of the little (tiny) check ball where the arrow is pointing in the photo?



Honestly, I'm a little unsure exactly what happens when the solenoid actuates the injector. I mean, what parts move and what, exactly, forces the needle up. I thought the solenoid lifted the entire needle up toward the top of the injector, but looking closer I'm not sure anymore.

The coil unlocks the needle and the check ball while rail pressure thru a small orfice the check ball plugs is used to "fire" the injector. The yellow area under the umbrella looking piece is the fire fuel apply on the lift plate.



Contamination, scoring, wear, etc, on these pieces cause a lot of the injector misfire problems. If there was small wear in this area rail pressure at idle may not be enough to suffieciently fire the injector, then, as rail pressure comes up it will start working better. A little delay in timing would not cause a lot of smoke but would impact the overall power and reduce mileage.





My . 02

 

[betterthanstock]

Honestly, I'm a little unsure exactly what happens when the solenoid actuates the injector. I mean, what parts move and what, exactly, forces the needle up.

The orange dots are the coil. They pull up the greeen disc. You see the spring, and the yellow travel adjustment bolt on the very top.

The disc, with the green stem, moves up (a few thousands of an inch) and allows the ball to move up.



The pressure comes in thru the rail, enters the hair-sized red orifice up, to the blue plunger. When the ball opens, fuel flows up thru anoher hair-like orifice around the ball.

(That fuel is wasted, it's returned back to the tank, so if you have excessive leakage to the tank, it's the fault of that ball, or the solenoid disc/plunger that is stuck; or a crack in the body that leaks into the yellow areas-- which represent low-pressure fuel returned to fuel tank).



When the ball is opened, it bleeds the pressure around the upper half of the blue spool, and pressure on the lower spool (high pressure fuel is shown in red) or injector plunger, compresses the lower spring and pushes both spools up, opening up the firing holes.



When the check ball closes, pressure builds up in the upper half again, pushes everything down, and it all closes up. Simple, but fragile, and dependent upon very tight fitting of the plungers, clear, unclogged hairlike orifices, leak free ball, and free moving coil assembly. Too tight a spool (due to rust or contaminants) will cause sluggish firing of the injector, so sometimes cleaning the spool may be all that is needed.



There is a balance between the two hairlike orifices, that controls how fast the little upper chamber empties, and fills up, which controls the opening/closing speed of the injector. The outlet orifice (closed by the ball) has to be slightly bigger. That way, the inlet orifice cannot fill up the upper pressure chamber when the ball opens. If the outlet orifice plugs up (rust, dirt) then it will open very slowly, if at all. If the inlet orifice plugs up (even partially), it will take too long to fill the pressure chamber, so the injector will remain open too long. (goodbye piston!!)



I think it's obvious that the inlet orifice, given that it is smaller, and it is at the INLET, is more prone to plugging up. Bad news for the engine, since that means it gets stuck OPEN.



This spool design has been around for maybe a hundred years as a hydraulic servo, even in power steering systems.



Those parts are fit with a clearance of microns, and just the heat from your hand, if you hold the spool in your hand, may be enough to cause it to jam when you try to reinsert it into the body.



I think do-it-yourself cleaning of the injector is not impossible, as long as you don't mix parts with other injectors. That ball, finding a new one, if it's bad, and readjusting the plunger travel distance, if necessary, that may be the biggest obstacle to the DIY'er.



BTW, this is a D-max injector. Notice on the inlet fuel fitting, which is different in our engine, that light gray part surrounded by red, is the EDGE FILTER. Fuel squeezes thru the tiny gap around the edges, and any metal particles from the injection pump, get stuck there until the pressure eventually breaks them into smaller particles, and they pass thru. Removing those filters, will allow particles to plug the hairlike holes, or jam the spools, and may cause the injector to stick open, or closed.