Knocking noise

[MMeier]

. . Changed nozzles and 2 injectors, have this noise now that comes and goes when it warms up, seems to be dependent on load/ throttle position. Installer says its because the pilot injection event has been cancelled out? Sounds almost like a small block chevy with a bad rod!

 

[Johnstra]

Why would the pilot injection event be cancelled out? What's that mean? Is it something wrong with the injector or is the ecm doing something to turn off pilot injection?



If you figure it out, let me know. That's what mine sounds like.



-john

 

[MMeier]

Why would the pilot injection event be cancelled out? What's that mean? Is it something wrong with the injector or is the ecm doing something to turn off pilot injection?



If you figure it out, let me know. That's what mine sounds like.



-john

When does your truck make this noise?

 

[rbattelle]

If pilot injection is turned off it stands to reason that the engine would sound similar to a 24v. It would NOT sound like a single bad rod, which is what I think you're saying it does sound like, MMeier.

When my truck was new, up until about 40k miles, it had a nasty (well, I thought it was nasty) knock just off idle (the infamous 3rd gen knock). It eventually disappeared, but I always suspected it was a fault in one of the injectors.

Since you just did a bunch of injector work, I place the blame for this new knock on a faulty injector.

Besides, I've never heard of any programmer or modification that successfully eliminated the pilot injection (except P-pumping the truck). Did I miss something?

Ryan

 

[Johnstra]

My truck makes noise when it reaches operating temp. When it's cold it idles normal and engine noise while driving is normal. As the engine heats, up I start hearing a what I call a tick (others might call it a knock). I hear it most under load at 1500-1800 RPM. At idle, I hear what I'm pretty sure is the #1 injector line hammering. I've listened using an improvised stethascope all over the engine and the only thing I can pin the noise to is the hammering #1 injector line. I don't know if the sound I hear under load is the same thing, but I suspect it is.



I know everyone says the #1 line is noisy, but I think mine is louder than most. Is it the injector making the noise or is it the unsupported line itself? From a performance perspective, my injectors are fine: starts easily, no smoke, good power, and good fuel economy.



I've heard the hard knock Ryan is describing. I had an injector go bad in my previous 03 and that off-idle knock is very distinctive. It sounds like someone's whacking on the block with a hammer. That one is easy to diagnose, too, by just individually turning off injectors until you find the one causing the knock. The sound I hear now is nothing like that. It's way quieter, but still very annoying.



-john

 

[MMeier]

My truck makes noise when it reaches operating temp. When it's cold it idles normal and engine noise while driving is normal. As the engine heats, up I start hearing a what I call a tick (others might call it a knock). I hear it most under load at 1500-1800 RPM. At idle, I hear what I'm pretty sure is the #1 injector line hammering. I've listened using an improvised stethascope all over the engine and the only thing I can pin the noise to is the hammering #1 injector line. I don't know if the sound I hear under load is the same thing, but I suspect it is.



I know everyone says the #1 line is noisy, but I think mine is louder than most. Is it the injector making the noise or is it the unsupported line itself? From a performance perspective, my injectors are fine: starts easily, no smoke, good power, and good fuel economy.



I've heard the hard knock Ryan is describing. I had an injector go bad in my previous 03 and that off-idle knock is very distinctive. It sounds like someone's whacking on the block with a hammer. That one is easy to diagnose, too, by just individually turning off injectors until you find the one causing the knock. The sound I hear now is nothing like that. It's way quieter, but still very annoying.



-john

If you run it "somewhat hard" up through the 1500-1800 RPM range is the noise lessened, vs. just going up through that range "normal"? And, short of going to a dealer, how do you turn off injectors one at a time?

 

[Johnstra]

That's right, if I run hard I don't hear it. Where I hear it most is climbing a steep grade just holding a constant speed. If I accelerate on a hill I don't hear it.



You need a diagnostic tool to do an injector kill test. I don't have one. My dealer did mine. You can also unplug two at a time, but I tried that and couldn't tell anything. The engine runs rough enough with two injectors unplugged that I couldn't tell. Guess you could pull your valve cover and remove the wire from one injector at a time.



-john

 

[RobertP]

anyone have any new information on there knocks?

 

[MMeier]

anyone have any new information on there knocks?

Nope, still there, went to L. A. with the big trailer the other day, man, does this thing make noise when hot!

 

[WUnderwood]

it knocks because the pilot injection shot is bigger than stock. it is bad for piston tops, etc, etc. mine does it too

 

[Johnstra]

My truck is stock and it knocks when hot. Still don't know why.

-joh

 

[Joseph Donnelly]

The FCA can cause fuel knock/clatter also. The specific size of injectors also affect the noise. Remember the 24 valves and how the sound changed with RV injectors.

 

[FFredrickson]

similar troubles

I have a terrible knocking in my motor. It sounds like a bad rod. I have minor aftermarket upgrades and the dealer said it wont warranty anything. #@$%! I will have a qualified mechanic look at it in one week to determine what went wrong. The dealer wouldn't even determine what was wrong before they said NO-WAY.

I hope this is just injectors. It will be a good excuse to buy some solid aftermarket ones. If this is more than that I will have to go to war with Dodge.

I will keep you informed of the results of diagnosis. We have checked the oil and there is no metal and no fuel in the oil.



06, 20k, Tripple dog, Snow WM, 4 inch lift, 35s, Fab four front, AFE

 

[MMeier]

I have a terrible knocking in my motor. It sounds like a bad rod. I have minor aftermarket upgrades and the dealer said it wont warranty anything. #@$%! I will have a qualified mechanic look at it in one week to determine what went wrong. The dealer wouldn't even determine what was wrong before they said NO-WAY.

I hope this is just injectors. It will be a good excuse to buy some solid aftermarket ones. If this is more than that I will have to go to war with Dodge.

I will keep you informed of the results of diagnosis. We have checked the oil and there is no metal and no fuel in the oil.



06, 20k, Tripple dog, Snow WM, 4 inch lift, 35s, Fab four front, AFE

Under what conditions does your truck make this "noise"? What "minor aftermarket upgrades" do you have?

 

[RobertP]

im hearing this concern more and more everyday. i have had two people call me saying that they are experiancing the same issue.

i know that mine has come and gone in the past two days. i was very exited when it went away completely for two day but now is back. could it be this new fuel and the weather change??

alittle more to add my truck runs like crap when cold, just under a light load it will sputter. soon as it warms up its ok again.

 

[Triton]

I've been having a time with this rattle myself. If you guys would... please take a listen to this video and tell me if it's the same rattle you're having.



You can hear it best towards the end of the video..... the underlying rattle is the normal Cummins shake. . the knock in my truck video

 

[RobertP]

Yup thats the noise! except sometimes mine is alittle worse. was that just from loading it up in gear? because mine doesnt do it in neutral. also i added some two stroke oil again tonight and the noise quieted down really fast after the fill up. thats why i believe that it is the fuel. and the colder weather.

 

[Triton]

That was in gear with the E brake on. It doesn't do it idling. I don't know about yours but, it's not the cold weather with mine. It has been down in the teens but, it's done it since the summer... mainly does it when warm and rolling into the throttle... at any speed.



It's very odd because my engine is built from the ground up and i thought that had a lot to do with it but, after seeing so many with the same issue I gotta wonder what else it could be beside the few reason I've ran across.....



CP3 gear lash according to some

valve lash

pilot injection out of wack

commanded and actual pressures off

bad injectors

bent push rods

bad programming from a downloader



I've rule out a few and I'm working on the others. Don't know that I'll ever find it as it may be the nature of the beast... I hope not, it's pretty annoying. At least it doesn't take away from power.

 

[RobertP]

you may be correct about the temp outside, because now that i think about it, it was in the 70's when mine first started acting up. mine does change from fill up to fill up. and the two stroke oil helped a bunch. i have has three different cp3's on my truck and the noise was still there with all of them. im slowly trying to eliminate some on that list also. i had my injectors gone through, ive replaced the cp3 twice, changed programmers, reflashed ecm with chrysler stock programing, checked my valve lash, and tried many different fuel stations with different additives. the best of all of them seems to be citgo fuel and two stroke oil.



i will pull my push rods when i put my bigger nozzles on, to check them.

 

[Triton]

you may be correct about the temp outside, because now that i think about it, it was in the 70's when mine first started acting up. mine does change from fill up to fill up. and the two stroke oil helped a bunch. i have has three different cp3's on my truck and the noise was still there with all of them. im slowly trying to eliminate some on that list also. i had my injectors gone through, ive replaced the cp3 twice, changed programmers, reflashed ecm with chrysler stock programing, checked my valve lash, and tried many different fuel stations with different additives. the best of all of them seems to be citgo fuel and two stroke oil.



i will pull my push rods when i put my bigger nozzles on, to check them.

Oh man... you busted my bubble. I was hoping a reflash would do something and was planning a trip to the dealer. Guess I'll go anyway cause i want to do a cut out test too although I had DonM check them. That wasn't in the truck though.



Tim@TRE told me he has the same issue and has had his head off three times looking for something including other components but, found nothing. No damage either from what he could see.



I think between everyone looking for the cause, somebody is bound to find something. I'll be sure to post it if I do !