LMM: Sligth "Pfft" under WOT shift/lockup

TowU4Free

#SecretSquirrel
Aug 27, 2011
457
2
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I posted on the Duramaxforum but i know knowledge here is more up my alley in this subject matter..Any of you guys running larger chargers experiencing any of this? If i do a WOT pass in my truck once it either locks the converter or shift i get this "Pfft" from under the hood/ not quite a chirping sound. Im trying to convince myself its a small burst of turbo surge with the stg2r 68mm but im not seeing any more boost with this charger then i did with the 3794, granted i have 100 over injectors now. 3794 never did this that i recall. Boost pressure is 35-40psi at the Y bridge when this occurs. It sucks trying to diagnose these things because WOT issues arent something you can pop the hood and have a buddy listen for!
 

TowU4Free

#SecretSquirrel
Aug 27, 2011
457
2
18
Im hoping you can tell me Yellowchevy, Im all to familiar with a bark or surge on a larger scale (choo choo choo choo) the split second "Chip" is a different animal, and why the 3794 didnt do it? Granted it had stock injectors then
 
Jan 28, 2015
962
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Ohio
Mine does this also Chris. Seems like a small turbo bark to me but what do I know? When mark drove it after it was tuned he said that it would make a certain noise bec it flows so much air but idk if this was the noise or not. I forget lol keep me updated though.:thumb:
 

TowU4Free

#SecretSquirrel
Aug 27, 2011
457
2
18
I was hoping you would chime in and say that shoot me a text when you get a chance
 

Verlon at ATP

New member
Mar 19, 2015
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Does it do it on every shift? Are your shifts crisp or do they have a little pause that would allow boost to drop some? My setup is a little different, but I do get some weird noises every once in a while. It is hard to go wide open though as I am traction limited on the street.
 

TowU4Free

#SecretSquirrel
Aug 27, 2011
457
2
18
not every shift . it may be on lockup only it only happens once and traction is not existent .. This morning it did it when it got traction and shifted.
 
Jan 28, 2015
962
0
0
Ohio
Mines usually 4-5 and 5-6 whe. Tc locks or is close to locking. As air flow boost and rpm falls off which leads me to think its a small bark. As for the limited traction I can't drive this thing in the rain lol
 

yellowchevy

Active member
Sep 9, 2010
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Louisburg, KS for now
Im hoping you can tell me Yellowchevy, Im all to familiar with a bark or surge on a larger scale (choo choo choo choo) the split second "Chip" is a different animal, and why the 3794 didnt do it? Granted it had stock injectors then
From my IHI testing, which is different than a VGT, but when I ran the batmowheel I would bark between shifts on hard accelerations and when towing; I'm running stock injectors as well.

That's what made me think of turbo bark with me getting between shifts on mine. That would be my guess but with not being there to hear it I'm not 100% positive.

Yellowchevy
 

TowU4Free

#SecretSquirrel
Aug 27, 2011
457
2
18
its like a split second! Like you said travis like tapping the schrader valve on a tire
 

MarkBroviak

DMax Junkie
Vendor/Sponsor
Yes it is the air coming out the map groove when shaft speed drops on the shift. You should hear my wifes truck do it, lol! You can hear her's from 200yards away as she is driving away from me. If the map groove was any higher in the cover then it would be a very crisp chirping sound but instead it is more of a rush of air type sound. This is the only turbo that I make that is this vocal about it too. It's part of it being so aggressive.
 

mike diesel

I'm alright.
Sep 6, 2012
4,005
0
36
SLC, Utah
Yes it is the air coming out the map groove when shaft speed drops on the shift. You should hear my wifes truck do it, lol! You can hear her's from 200yards away as she is driving away from me. If the map groove was any higher in the cover then it would be a very crisp chirping sound but instead it is more of a rush of air type sound. This is the only turbo that I make that is this vocal about it too. It's part of it being so aggressive.
Mark, I want this turbo so bad. FML!
 

clrussell

pro-procrastinator
Sep 23, 2013
5,552
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I wonder if my buddies 72 is doing the same thing? I've never heard it so I don't really know what it sounds like


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clrussell

pro-procrastinator
Sep 23, 2013
5,552
104
63
We think his is a boost leak just havnt really has time to mess with it


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TowU4Free

#SecretSquirrel
Aug 27, 2011
457
2
18
From what i understand only the R series turbos are being as vocal..Im glad to know its normal for the charger, After replacing the copper washer on injector #8 twice now after the 100s had me worried something else is to blame! Still dont know why that injector has had issues multiple times
 

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