LMM: 2008 Dmax Loss of Power and Air Noise

Jun 8, 2015
5
0
0
Tennessee
Recently my 2008 GMC duramax has suffered a devestating loss of power, accompanied with a sound inside the cab that sounds like air coming through the vents. Upon heavier acceleration, the air sound gets louder. The truck rarely smoked but it has started smoking excessively. Cleaned the air filter, inspected the entire intake, inspected the turbo hoses, found nothing. Any thoughts? Oh, and the gas mileage has dropped off the charts as well.
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,704
765
113
Texas!!!
Look and see if the intake neck blew out of the intake crossover bridge between the heads. You'll have to look down in the valley behind the CP3.
 

Awenta

Active member
Sep 28, 2014
4,090
2
38
CT
What kind of boost are you seeing?

Check the bellows? And egr as Josh said.

Pressure test. Quick and easy.

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clrussell

pro-procrastinator
Sep 23, 2013
5,928
399
83
Also check the hard plastic connection at the passenger side of the intercooler where your egr delete connects.


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hdrolling

Freedom Defender
May 11, 2011
61
2
8
Fayetteville, NC
Did you ever get this fixed?

I had my boost tube boot tear while traveling and it was a pain, loss of mileage, lots of black smoke, loss of power, and the reduced power warning and limp mode.

We were towing an enclosed motorcycle trailer with our Harley at the time plus had the kids and two dogs. Luckily it happened on the way home and we were able to limp back so I didn't have to pay a shop to find and fix the issue.

Replaced the stock tube and boots with a Banks boost tube, issue fixed.
 

Bonestock

Active member
Aug 9, 2010
1,358
1
38
Worland Wy
Tig weld your y bridge or replace it with an hsp hi flo y bridge. The stock unit is a pos escpecially with certain egr delete kits as mentioned above.