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

[Smokem]

Originally Posted by jasonc

I understand, and don't want to spread bad info. But a normal guy with a mild street truck, who doesn't own a diesel timing light it's a decent option.

I don't disagree it is an accurate method, and a good way to verify in comparison to plunger lift, but neither can/will take into account all of the variables. Sound advice would be to try the timing in a few areas no matter the method used and see how it responds, and stick with what works.

[CorneliusRox]

Originally Posted by Smokem

We verify injection timing with a light on the engine dyno before each session, it is very common to see the assumed value 5-8° low compared to measuring it at the injector. This is very important in a competition surrounding as 3° in the right direction can often yield in the neighborhood of 100hp. I can understand that this isn't an option for everyone, but to say that setting the timing via the damper is the only accurate method is quite naïve.

Originally Posted by Smokem

I don't disagree it is an accurate method, and a good way to verify in comparison to plunger lift, but neither can/will take into account all of the variables. Sound advice would be to try the timing in a few areas no matter the method used and see how it responds, and stick with what works.

I think you misunderstood me. I by no means think by the damper is the only accurate method.
I agree a timing light is more accurate.
And more than anything, I agree you should start at a number, but massage based on how the truck responds.

I think we're saying the same thing. Timing light is very accurate, but damper is likely good enough for street trucks. It's also free to do with standard tools, and pretty easy to do.

[Smokem]

Originally Posted by CorneliusRox

I think you misunderstood me. I by no means think by the damper is the only accurate method.

I did not misunderstand, I quoted your comment based on the insinuation you need a "race engine" to necessitate a timing light. My advice to people is to never miss an opportunity to do something right, no matter the budget. In my experience either way(balancer vs plunger lift) is as accurate as the other, it's more the man than the method that tends to be the issue.

[GAmes]

Originally Posted by AMS247

.........but I've also read that the TDC pin for the back of the cam gear itself can have up to 3* of fluctuation?

If that is true, without removing the head would it be more accurate to do the drop valve method of finding TDC?

True. The cam pin housing is adjustable. The adjustment procedure in the FSM is the procedure commonly called the drop valve method.

[jasonc]

Another easy way to find tdc, remove #1 injector.
Take the injector hold down nut and get a peice of 1/4" allthread and 2 washers that fit inside the hold down nut.
Put a nut on both sides of the washers to secure the peice of all thread.

Cut the length of all thread to where it contacts the piston before it's full upward travel, say like 1/4" before full upward travel.

Then roll the engine forward until it hits the stop, then mark balancer there. Then roll the engine the opposite direction and mark the balancer there.
In between those 2 marks is true TDC. Make a permanent mark there and you always have it.

Also remember to do this procedure after turning the engine clockwise while looking at the intake valve, as soon as the intake valve is closing, then put the piston stop in and make your marks, so not to be 180 degrees out.

[jasonc]

Or PM Vincejax on here. He has made up an adjustable piston stop that does the same thing.

[AMS247]

So I received the new injector set and installed them today. I did take a closer look at the markings on the bodies and noticed that on the 1st set that I am switching out were stamped 240 Bar, and the new set is stamped 262 Bar. Not that it matters since they were gone through and adjusted anyways by the sounds of it, but I didn't think P-pump injectors were made under 260 Bar. I was sold the 1st set was benched at 280 Bar, and this new set is at 290 Bar.

This new set is the same thing, 5x14 SAC injectors. These do NOT have the edge filter removed and I am guessing that there is no needle work done like on the 1st set.

Following installation of the new set. There is improvement. The sound I heard is still there but it has dimmed down and it goes away even lower in the RPM.

Were earlier, I said that the sound was loud til 1,800 RPM and was gone by 2,000 RPM.

On this new set, the sound was loudest til 1,600 RPMish and gone by 1,800 RPM.\

Overall, it was definitely quieter than the 1st set.

The engine and the exhaust sounds good at idle too. I feel like I'm being nit picky because it seems the engine may be vibrating slightly more at idle from what I recall, but I honestly have no idea but thought I'd mentioned it if it helped at all.

I'm going to check timing and play with that since that's my only other thing to adjust..

[AMS247]

Adding more before I change about the timing.

I cold started the engine today, about 60* outside and RPMs in Park or Neutral were about 900 and then once I put the truck into gear they dropped to about 750 and the engine was slightly loping. This goes away after a few minutes of driving. But something I never experienced with factory injectors with all other mods the same.

[jasonc]

Man that's kinda normal, idle it up a little.

I think you may be just listening to things to much.

[AMS247]

I went snow wheeling today with the 2nd set of injectors. They definitely sound worse in some ways than the 1st set.

There was quite a bit of smoke haze blowing out in front of me even when the engine was warm.

They also seem to run hotter than the 1st set. Both being 5x14 size. I was able to get the EGT guage up to 1200 it seemed rather easily.

I'm going to be checking timing and playing with that the next free day I have to do engine work.

I'll report back then.

[AMS247]

Updating this thread:

I checked timing and it was in fact off from where I thought it was.

My engine came factory at 14* so I pinned the pump there.

Found TDC by doing the drop valve method and the magnetic degree wheel from PDD on the dampr. and Timed the engine at about 18.5*.

The Sound is most definitely still there..

I'm going to swap back the first set of injector that I was given with a pop pressure of 280 Bar and see if THOSE sound any different now with the timing at 18.5*.

Also to note, I can clearly hear the sound inside the cab while driving. But from what a helping hand as said, they don't hear anything outside the truck..

[AMS247]

Still struggling with this problem.

I swapped back in the first set of injectors that I received and it does sound better than the 2nd set now with timing at the 18.5*.

Going from the 2nd set of 5x14s with 190 Bar pop pressure to the 1st set of 5x14 with 180 bar pop pressure and edge filters removed with needle work:

Engine starts easier.
Idle is smoother.
more power FEELS there.

STILL having that weird thump type sound on lower rpm acceleration. Not as prominent as before with the lower timing.

I'm lost where to look next.. I'll play with the smoke screw some and see if maybe there is too much fueling lower in the boost?

[AMS247]

Is there anything with the way the needle seals itself inside the body that would make an injector pop but be off still?

These injectors are smoother than set #2. Trying to put fresh ears on this issue, the factory injectors still sound healthier..

Idle sounds slightly rough either hot or cold, idle RPM is 850.

Truck sounds fine with no load. Under load accelerating slowly it's noticeable.

Accelerating with more fuel and more on the pedal it isn't as noticeable..

Idle to 1800 rpm ish is where I hear i Above that I have said before that it was gone, but maybe it's just not as noticeable because of the RPMs and less load.

Being at a stop light with other vehicles around, I definitely hear it more off the engine..

I'm at a point of just throwing the factory sticks back in and putting this issue on the back burner.

[AMS247]

Just updating this with an ending for anyone reading.

It came up on another forum that my issue is most likely injection pump related..

So my options are to live with the sound, rebuild the pump or keep the factory injectors in the engine.

I'll probably ride this out with rebuilding the pump later down the line.

[Snedge]

Originally Posted by AMS247

options are to live with the sound,

You should have made that the first option instead of chasing your tail.
Twelve valves are noisy to begin with, and adding fuel makes them noisier. The good news is you've got some good practice at setting valves, timing, and replacing injectors.

1. Run it, and love it..
2. Buy a common rail.

Back in the "Mack turbo is the way to go" days, I had one timed so high that it sounded like a bag of marbles pouring over the valve covers when you rolled into the pedal, but once the turbo lit, hang on.

[Smokem]

Originally Posted by AMS247

It came up on another forum that my issue is most likely injection pump related..

Why would the injector change have an impact if this was the case?

[AMS247]

Originally Posted by Snedge

You should have made that the first option instead of chasing your tail.
Twelve valves are noisy to begin with, and adding fuel makes them noisier. The good news is you've got some good practice at setting valves, timing, and replacing injectors.

1. Run it, and love it..
2. Buy a common rail.

Back in the "Mack turbo is the way to go" days, I had one timed so high that it sounded like a bag of marbles pouring over the valve covers when you rolled into the pedal, but once the turbo lit, hang on.

I'm fine with noise.. it sounds off though. Like there is some sort of miss within a cylinder to me.. (my uneducated hypothesis) since Idle is slightly more rough than the factory injectors and the sound can be heard through the RPM range under load conditions.

I had a buddy riding in my passenger seat yesterday and from that side of the truck with the window down he heard it more from the exhaust pipe than the engine.

It almost sounds like a more milder sound of what it sounds like loosening an injection line while the engine is running. Not as extreme, but similar to a lesser degree.

Originally Posted by Smokem

Why would the injector change have an impact if this was the case?

It sounds like if one of the plunger/barrels on the pump has a defect not producing pressure correctly that the higher pop pressures of 280 & 290 bar are struggling compared to the 200k miled factory injector pop pressures.

That's the short version of what was concluded.. is this not usual?

[Vincejax]

Originally Posted by AMS247

I'm fine with noise.. it sounds off though. Like there is some sort of miss within a cylinder to me.. (my uneducated hypothesis) since Idle is slightly more rough than the factory injectors and the sound can be heard through the RPM range under load conditions.

I had a buddy riding in my passenger seat yesterday and from that side of the truck with the window down he heard it more from the exhaust pipe than the engine.

It almost sounds like a more milder sound of what it sounds like loosening an injection line while the engine is running. Not as extreme, but similar to a lesser degree.



It sounds like if one of the plunger/barrels on the pump has a defect not producing pressure correctly that the higher pop pressures of 280 & 290 bar are struggling compared to the 200k miled factory injector pop pressures.

That's the short version of what was concluded.. is this not usual?

If you have a defect on your P&B assembly I don't see it holding together for long. Also injection pressures are WAY above injector pop-off pressure. Your pump isn't going to struggle to inject past a few more bar of pop pressure. If you are already this deep into your diagnosis yourself, might as well get an injector pop tester and timing light and keep digging yourself until you find it.