Engine Seems Louder (maybe knocking) in Low RPM Range

[hdpwipmonkey]

So, for the last few weeks my truck seems to be louder than normal.  Almost sounds like a knocking but only hear it in lower RPM limits (less 1200 rpm).  I don't know if its just me or not.  I don't have any CEL on or any codes that I can see with my Bluetooth OBD2 scanner.  I don't see any smoke and the truck runs good.  I did start getting diesel at a different station (Chevron instead of Fred Meyer).  Could it be a difference in diesel?  Could it be colder weather?  It does it with the Quad at 0, 2, 3 or up.  It does it with the daily tune and the performance tune.  I can really notice it at cruise with light throttle.  Any suggestions.  This is my first winter with the truck so as far as I know this could be normal. 

[Mopar1973Man]

High cetane fuel could produce more knock than usual. 

 

Each brand name carries its own additive package before being delivered to the fuel station. I typically stick to larger brand names Chevron, Shell, Maverik, etc.

[hdpwipmonkey]

2 hours ago, Mopar1973Man said:

High cetane fuel could produce more knock than usual. 

 

Each brand name carries its own additive package before being delivered to the fuel station. I typically stick to larger brand names Chevron, Shell, Maverik, etc.

Ok.  I will swap back to where I was originally getting fuel and see if it changes.

I wasn't sure if it was maybe a timing issue or something.

I did notice that my engine load toggles between 4 - 5 at idle according to my Quad and it seems to be idling high, usually around 920-ish so I think injectors are in my near future too.  165k on these ones.  The guy I got the truck from rebuilt the motor at 155k but used the same injectors 

[Mopar1973Man]

Injectors are shot. Set idle speed is 800 RPM. This means the ECM cantcut fuel any deeper and the pop pressure is really low.

[hdpwipmonkey]

2 minutes ago, Mopar1973Man said:

Injectors are shot. Set idle speed is 800 RPM. This means the ECM cantcut fuel any deeper and the pop pressure is really low.

That's what I figured.  New injectors, headstuds, and valve lash adjustment is next on the list...

[hdpwipmonkey]

Can I try advancing the timing a little to offset the low pop pressure of the injectors to see if that helps?

[Mopar1973Man]

I found that cruise of 21* or so at 2k on the tach was a good spot. Once I got the injectors replaced the timing had to be retarded. Now that mine are settling it can be advanced again.

 

[hdpwipmonkey]

I notice it more in the low end of the RPMs.  1500 or less.  Usually just starting out or while cruising at lower speeds around through town.  When at highway speeds or if I'm really getting on the throttle I don't notice it.

[Mopar1973Man]

What do you have for timing set up? Or upload the tune for me.

 

[hdpwipmonkey]

Here are the 2 tunes I've been using.

 

 

iQuad-Mopar1973man Performance-2019-03-15-08.27.04147447478196055003.json iQuad-daily-2019-03-15-08.26.444726115227942262255.json

Looking at these tunes in the tune builder they do look a little low on timing.  The daily one isn't as bad as the performance one (if I'm looking at it correctly).

[Mopar1973Man]

Neither of those look bad. Starting at 14.5 or 15 is fine for nearly stock injectors.