Weird "Burping" sound from Turbo when letting off the accelerator

[Cummins4WD]

While climbing a mountain pass or stepping on the accelerator I hear a strange "burping" sound coming from the passenger side of my Cummins 305/555... It seems exhaust related like around the turbo area... Is this normal or could a sleeve or part of the exhaust be loose?



If I step on the gas and let off it does it but more so when the truck is going up a steep hill and I let off...



Is this Turbo Bark and is it bad for the Turbo/engine? It seemed to happen several times on a 1000 mile loop around Southern Colorado over the weekend. Mostly going up passes and slowing for corners, etc.



Would going up to a full 4" exhaust help the situation at all. I'm sure I just need to let off the fuel slower. Any advice?

 

[DLeno]

I think you need to head for the dealer. what you describe is not normal for the stock truck. I'm assuming you have no power mods, is that correct?

 

[CJEliassen]

It's your waste gate opening and closing. It is perfectly normal, so don't worry about it

 

[BCarmicle]

I've heard/felt something similar from my truck. When letting off of it the truck kind of bumps sometimes. I usually only notice it when I turn my TST box to levels 4/4 and up.

 

[DLeno]

I sure never heard any 03-04s burp. with mods yes, but not stock.

 

[Cummins4WD]

I'm fairly certain I don't have any mods... I bought it used in Texas so maybe there's an EZ box hiding under the hood... I highly doubt it though. I'll try and get a sound byte with my Mac PowerBook this week. She's all OEM with 31K on a 305/555 HO...

 

[jcarey]

II did, last Saturday morning, on the way to work. I don’t know if I would have heard it without the AFE. I was going through downtown and approached a rather quick changing light (that I know has cameras ). As the light started to change. I knew I was going to end up in the middle of the intersection with my picture being taken :{ . Sooooo, I punched it Oo. . As soon as I got through the light, I popped my foot off the pedal to get MPHs down fast (before I ended up running the next light about ¼ mile up the road :-laf ). That’s when that darn turbo barked at me :--) .

 

[DLeno]

yea, I hear my turbo now too, with the AFE on. bone stock trucks shouldn't hear it.

 

[CJEliassen]

I have a bone stock 600 and I hear it just about everyday.

 

[KBennett]

Maybe it's altitude related?



I have a bone stock '04 555 and I can do it and so can crobertson1 in his bone stock 600. It happens when we are pulling a trailer and have to downshift to slow down for another vehicle and then pass.



You have to learn to let up a little slower.

 

[ZRamsey]

mine does it sometimes when i let off the skinny pedal to shift going WOT :-laf to merge into traffic.

 

[CJEliassen]

Maybe it's altitude related?



I have a bone stock '04 555 and I can do it and so can crobertson1 in his bone stock 600. It happens when we are pulling a trailer and have to downshift to slow down for another vehicle and then pass.



You have to learn to let up a little slower.

Thanks for the advice. I didn't know it was hurting anything. What exactly am I hurting by letting the waste gate open? Been driving a diesel for years and I never knew I needed to learn to let up a little slower.