New member needing help!

[Nutznky]

Posted this question on another site and not one single person would help. Hoping someone here will have an answer.


Hello all! I have an 04 LB7. EFI Live, cold air intake, 5 inch exhaust and a boost valve are the only mods. Truck runs flawlessly. When building boost, at right around 7 and a half to 8 pounds, I get this rattling sound. This only occurs on stock or economy tune. Anything hotter and I don't hear it. Just wondering what it could be because as stated, the truck runs fine. I've drove it on several 3-4 hundred mile trips and never an issue. I'm kinda new to these trucks and just wanted to be sure there wasn't a problem. Thanks in advance for your help!

 

[DAVe3283]

Odds are you are at around 2500 RPM, which is where pilot injection turns off. Pilot injection is what makes modern trucks so quiet compared to old diesels.

The rattle is normal for light load without pilot injection, and is harmless. You don't hear it on bigger tunes because under high load the engine is injecting fuel for so long it doesn't rattle.

The only way to know for sure is to hook up a scan tool and record what is happening when the rattle happens. But odds are it is pilot injection turning off.

Sent from my S60 using Tapatalk

 

[Nutznky]

Kind of what I was leaning towards after doing some research. I'll check to see what rpm range it's in next time I drive it. It's done it ever since I've owned it and I daily drive it so I about knew it wasn't anything to worry about. Any way to shut it up other than running a hotter tune?

 

[Nutznky]

And thank you for your help! Some of these other forums aren't real friendly which kinda defeats the purpose. I don't know a lot per say, but I will help anytime I can.

 

[TheBac]

Could be anything. We are not there to inspect your truck.

What kind of diagnosic have you done so far other than "I hear it stock/econ tune"? What have you ruled out in checking out your truck? Have you removed the tuner and tested it under same conditions yet?

If you cannot figure it out, your best bet is to take the truck to a respectable shop and get the tech there to drive the truck and help you diagnose it.

 

[2004LB7]

You mentioned that you have efi live, who's tuning? This can also be a reason, timing or fuel pressure being off can cause it. As mentioned above, can you log boost, injection quantity, timing and fuel pressure?