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Old 03-21-2020, 06:17 PM   #1
AMS247

Name: AMS247
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Too high of timing, effect low RPM sound? Injector Rattle?

I posted up here a couple months ago, and in that thread I found that what ever was making the sounds that I didn't like was contributed by the new injectors that I had installed.

With these new injectors, it made a weird sound, only under load that I would have described as a similar sound to a gas v6 engine exhaust manifold leak. The sound sounded air related, maybe even like the valves were out of spec. I checked valves a few times and they are at perfect Cummins Spec.

I swapped back to the factory injectors that I had and everything sounded perfect in the engine once again.

I'm having trouble with hands on communication with the injector company that I've done business with and frankly I am a noob when it comes to this sound.

Right now, my truck has upgraded fuel plumbing, keeping 25 psi at idle and keeping north of 30 psi up to 45 psi while driving.
  • 4k GSK
  • S362 SXE
  • 18* Timing
  • O-ringed Head
  • Hamilton Valve Springs and Pushrods

With the factory injectors, they have about 200k miles on them from what I know, and they do seem to be going out if I were to give my uneducated guess.

These new injectors are 5x14 SAC with the edge filter removed and needle work. New Bosch Nozzles on New Bosch Injector Bodies.

I sent them back to be looked at by this company 2 months ago and just received and installed them this week.

Anything below 1,800 RPM I can hear this sound in the cab very easily. Up to 2k I still hear it but it's not as prominent. From 2k to 3k even under load accelerating up a hill, the engine sounds perfect.

Is this just something to do with timing, and not the injectors themselves? I keep reading about Injector Rattle but I can't find a video to understand if that is what this is.

Is this a sound that I'm hurting the engine?

Also to add:

The engine starts up fine. In Park or Neutral the engine idles as the same RPM that the factory injectors Idled at.

Only when the engine is cold, do these new injectors drop to a lower RPM than the factory ones once I put the truck in gear with the first start up.

2 Months ago when it was much colder out (40-50*F) it would drop low enough to lope. Now (70-80*F) after I received the injectors back it doesn't lope, but does drop more RPM than the factory ones have been.
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Last edited by AMS247; 03-21-2020 at 06:24 PM.
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Old 03-25-2020, 10:22 AM   #2
SCHMITTY
 
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P pump 12 valve’s isles go up and down with the temp. Adding fuel will also change the idle characteristics. The injectors you installed probably have a different pop pressure and they may cause the differences your hearing also. These motors make a bit of noise regardless.

Who’s injectors ?
Can you hear the noise on video ?
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95 rclb, K31 71/76/.9, 180 pump, 5x.018s, 7mm dv , stock stall triple, nawz

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Old 03-25-2020, 01:31 PM   #3
AMS247

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Quote:
Originally Posted by SCHMITTY View Post
P pump 12 valve’s isles go up and down with the temp. Adding fuel will also change the idle characteristics. The injectors you installed probably have a different pop pressure and they may cause the differences your hearing also. These motors make a bit of noise regardless.

Who’s injectors ?
Can you hear the noise on video ?
Video Clip:
12vproblem1 - Google Drive

Audio Clip:
Weird sound 6bt12v - Google Drive

I can't hear the sound in all speakers. And I need to have the volume up on my stuff to hear what I am talking about.

I guess is sort of sounds like a jake break while under load in the lower RPMs... I don't have an exhaust brake and it's only under load. If I let off the fuel, it sounds fine.

And, once I'm above 2,000, it sounds great.

Having the factory injectors in, with all the conditions exactly the same. This jake brake type sound isn't there.

As far as the company name I don't want to show that yet depending on if this situations IS an injector problem and they're lagging on doing something about it. Contact with them has been difficult but I'll PM you.
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Old 03-25-2020, 01:56 PM   #4
AMS247

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The other thing that I will add. Is that I have noticed that shifting above 2,500 RPM with an unlocked converter the turbo slightly surges. This is at approximately 30 psi.

I do have a built auto with a FMVB. Lower stall converter so I would imagine it is just because of the drop in RPM. BUT, that is also a change that I had noticed.
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Old 03-25-2020, 03:19 PM   #5
jasonc

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Worse case scenario if an injector is faulty/damaged, and the needle not sealing or stuck, it could cause a fuel knock or just a dead cylinder and skip.

What's timing set at?
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Old 03-25-2020, 05:14 PM   #6
AMS247

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Quote:
Originally Posted by jasonc View Post
Worse case scenario if an injector is faulty/damaged, and the needle not sealing or stuck, it could cause a fuel knock or just a dead cylinder and skip.

What's timing set at?
Good to know that it won't do any damage to the engine running like this..

Timing is set at 18*.
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Old 03-26-2020, 01:23 AM   #7
SCHMITTY
 
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How was the timing set ?
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95 rclb, K31 71/76/.9, 180 pump, 5x.018s, 7mm dv , stock stall triple, nawz

2006 mega cab Stock grocery getter with a straight pipe and exergy sportsman injectors.
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Old 03-26-2020, 03:11 PM   #8
AMS247

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Quote:
Originally Posted by SCHMITTY View Post
How was the timing set ?
Dial indicator on the #1 delivery valve holder.
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Old 03-26-2020, 03:35 PM   #9
jasonc

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So in other words, you really don't know what the timing is set at.

Do you know how to set the timing off marking the balancer? Only really accurate way
I'll explain it if need be.
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Old 03-26-2020, 04:05 PM   #10
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The only accurate way is with a timing light.
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Old 03-26-2020, 04:59 PM   #11
AMS247

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Quote:
Originally Posted by jasonc View Post
So in other words, you really don't know what the timing is set at.

Do you know how to set the timing off marking the balancer? Only really accurate way
I'll explain it if need be.
Would you be referring to putting a degree wheel on the balancer and using the factory pump pin to use as a base line?

I do have a magnetic degree wheel to do such. If that is what you're referring to. Is that more accurate than the dial indicator method off the pump?

I don't have a timing light.. if it's not too pricey I would be open to buying one to give it a shot.

I talked with the company today. They are sending me a new set of injectors with higher pop pressure to see if that is the issue.

The response in this thread from PDD is the only thing on the internet that I can relate this experience to without further detail.

injector pop pressure question - Dodge Cummins Diesel Forum

The injectors were checked for pop pressure when I sent them back and they all checked out within spec of each other. Maybe the pop pressure overall is too low? I do not know the current pop pressure's of these to add...
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Old 03-26-2020, 05:56 PM   #12
jasonc

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All you need is a coat hanger wire.

Roll the engine until the pump can have the pin inserted, you don't even need the pin, just put the flat in the window.

Knock the pump gear loose.

Pin time the engine with the push in button that goes in the back side of the cam gear.

Make a pointer out of coat hanger wire and mark the balancer.

Divide the diameter of the balancer by 360 and make marks on the balancer for the amount of travel for timing advancement. Then back the balancer off to your new mark, good idea to roll the engine back farther then go back to your mark, to get rid of any gear slack.

Starting off with a base timing of 13, which most stock pumps are pinned timed at, or close enough.

Then torque the gear back on.
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