turbo surge

[snowmizer]

noticed over the past 2 weeks that when you get into the throttle and turbo gets going , that when you let off, that i get what feels like a surge. like the turbo is still boosting. foot is completely off pedal, and your comming to a stop. took a quick look at the rubber boots and clamps, thought maybe had loose clamp or bad boot, dont feel and rips or anything is loose. its not a surge from the transmission either. truck is stock, 05 h. o. ,auto

 

[JApol]

What you are doing is huffing the turbo. Diesels don't have blow off valves like the gassers. When you go from full boost and let off there is not enough gas coming out of the exhaust manifold to keep the air pressure up on the intake side and no demand for the compressed air on the intake side.



Thus the compressed air on the intake side blows out the compressor of the turbo. It sounds like a WHOOOSH!!. If you huff the turbo enough you WILL snap the turbo shaft.

 

[snowmizer]

i have never heard that sound. i'll have to pay more attention to see if i can hear it. thanks for the info.

 

[snowmizer]

and thats why i feel the surge ?

 

[snowmizer]

is this normal, or is their some other problem. never noticed this before. how can i make it stop. should i not let off the peddle so quick? does not do it towing.

 

[JApol]

I think I misunderstood what you were talking about but no you should not let off the go pedal all at once. Just gently let off and let the boost gently bleed off. I had a hard time hearing it till i got my aFe intake and I could really hear it.



When you let off the pedal like you are talking about, can you see any smoke coming out of the tail pipe?

 

[WCPoe]

Not bark or surge????

I think what Snowmizer is referring to is when you have accelerated and built some boost and then let off the engine still seems to be pulling. I had noticed that a time or two in close quarter traffic, usually when I'm taking off from a light and the guy in front of me decides to stop and turn with no signal. I kinda "wrote it off" as just residual boost but it may be an electronic glitch with the fueling software.

I also believe there had been some issues with the Smarty continuing to pull after you let off the go pedal but I hadn't heard anything about it lately. Anyway, it's definately different than what I think is turbo surge or bark because my SPS66 turbo will "woof, woof" if I want it to. Just my 2 cents.

Bill

 

[snowmizer]

i guess you can say its more like a lunge. only after throttling out ,just when letting off the peddle,like the turbo is releasing extra boost . as your slowing down . l have no turbo bark.