Knocking noise

mississippiray

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Nov 10, 2023
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i have a 2018 duramax 150,000 miles i have owned truck for 3 years purchased used and it coded the first day i had it def deleted and after delete started hearing a knocking noise
when traveling down interstate and reduce speed by just getting off the accelerator and coasting the engine will knock and if i apply brake hard it will stop or start to accelerate again it will stop
hunting solutionplease
 

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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Moved to L5P section.

What were the codes? Does the knock sound like its coming from on top of the engine or does it sound as if its under the truck?
 

kidturbo

Piston Tester
Jul 21, 2010
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www.marinemods.us
My thoughts are tune table related. Possibly a change to fuel pressure, pilot injection, or timing that you are now hearing under certain conditions. If that is the change that brought on the noise, I would bring that up with the tuner. Doesn't sound like hardware issue to me.
 
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2004LB7

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Dec 15, 2010
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Sme of the L5Ps also suffer from the same or similar injector connector issues like the LLY did. Some symptoms are knocking. Might be worth looking into ot
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Sme of the L5Ps also suffer from the same or similar injector connector issues like the LLY did. Some symptoms are knocking. Might be worth looking into ot

Truck will code if that’s the case… unless the codes were shut off

Knocking in decel sounds like a tune issue. Trucks probably trying to run its injector timing test and can’t due to only partially being tuned out or tables not corrected.
 
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mississippiray

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Motor Ops
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4"exhaust all the way
Could this be an exhaust leak there is a couple of sections that show a little bit of carbon buildup at the section joints
 

JoshH

Daggum farm truck
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Try doing an injector small quantity reset with a good scan tool.
 

mississippiray

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Nov 10, 2023
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Brandon Ms
I have tried to attach a video but i can not get the video from phone to laptop without it saying it does not have encoding setup so it want play on my computer or download to the conversation
if anyone has a suggestion for this also im open

thanks for help
 

2004LB7

Well-known member
Dec 15, 2010
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I have tried to attach a video but i can not get the video from phone to laptop without it saying it does not have encoding setup so it want play on my computer or download to the conversation
if anyone has a suggestion for this also im open

thanks for help
From your phone, upload it to YouTube then post the link here