LLY: Weird knock at heavy throttle.

Kspen90

Kspen90

<<<got turbos?
Jul 14, 2011
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Mine makes the rattling all the way from idle until the exhaust drowns it out no matter how hard i push the throttle. Its not nearly as loud or fast as the video, the speed just increases with rpm in a uniform fashion until it hits 2700 rpm then it rattles like hell (similar to the video) and takes off like i floored it even if im only at half throttle. Are these symptoms just normal characteristics of the duramax and im being paranoid or do i have a problem. I should add the truck has had the same setup for close to a year now with no problems knock on wood
 
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Dan@PPE

Diesel Enthusiast
Aug 8, 2006
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So Cal.
Kspen90 said:
Mine makes the rattling all the way from idle until the exhaust drowns it out no matter how hard i push the throttle. Its not nearly as loud or fast as the video, the speed just increases with rpm in a uniform fashion until it hits 2700 rpm then it rattles like hell (similar to the video) and takes off like i floored it even if im only at half throttle. Are these symptoms just normal characteristics of the duramax and im being paranoid or do i have a problem. I should add the truck has had the same setup for close to a year now with no problems knock on wood
Click to expand...

Can you try a stock tune? or somthing a little smaller? let us know the outcome!

Who modified your injectors?
 
Kspen90

Kspen90

<<<got turbos?
Jul 14, 2011
1,433
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Burleson, Tx
Dan@PPE said:
Can you try a stock tune? or somthing a little smaller? let us know the outcome!

Who modified your injectors?
Click to expand...

Right now im running the factory tuning from gm, and i got my injectors from us diesel parts and iirc they use exergy honed tips but its been awhile since i had them done.
 
PAT

PAT

EASY DAY
Aug 21, 2011
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Dan@PPE said:
I hate to use this as an example but you can clearly hear it in this video before the engine gives up. This is what injector/timing rattle sounds like, However much more server with nitrous. This was done with too much nitrous too soon. Similar sound but it won&rsquo;t be as loud without the nitrous..

sorry for using this video as an example

http://youtu.be/5perV0v6lkk
Click to expand...

Yep. That's what my truck sounds like. :( I just pooped out my morning coffee.
Anyone wanna come tune my truck!!!????

So I'm guessing that I should just stay on the smallest tune possible till I get this fixed. FML
 
DMAXDOC

DMAXDOC

New member
May 26, 2011
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Well after looking into it deeper on my LB7 it seems that when I turn off the water/meth it quiets down drastically. Must be too much/too soon ???
 
PAT

PAT

EASY DAY
Aug 21, 2011
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blackdirtymax said:
I think it is Dan , unfortunately I don't understand why so
Many of us with tuned trucks have it so bad ?? Lmao


---
- Built motor , duel fuelers , 60's overs , gtx4202r
Click to expand...

Bc some of us simply don't have the knowledge to build a good tune. So were in the hands of other "tuners" my truck was tuned by a reputable shop thats well known. So I don't know why my truck is doing this.
 
blackdirtymax

blackdirtymax

New member
Apr 15, 2010
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PAT said:
Bc some of us simply don't have the knowledge to build a good tune. So were in the hands of other "tuners" my truck was tuned by a reputable shop thats well known. So I don't know why my truck is doing this.
Click to expand...

That was my point


---
- Built motor , duel fuelers , 60's overs , gtx4202r
 
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Dan@PPE

Diesel Enthusiast
Aug 8, 2006
2,570
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36
So Cal.
How many miles on the engine? have the heads been off before? It almost sounds like the valves or a valve needs to be adjusted.
 
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