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Weird noise after S&B cold air intake install

10100 Views 9 Replies 5 Participants Last post by  Greg687
So when I let off the go pedal, I get a cross between a cat hissing, and whoosh of air coming from the truck. It lasts for like a second.

I thought maybe I was hearing turbo noise that I couldn't hear before the 4" turbo back exhaust, but then I read it is air coming out of the larger aftermarket intake.

Can anybody confirm that?

It is really loud when shifting into OD/4 under load while pulling my toy hauler.

Sounds similar to this guy's video:
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hope you respond. It sounds like I have the same issue. Did yours turn out to be the intake after all? Or did it turn out to be something else. I put on a whole new turbo and that damn sound still happens.
His was the new airbox allowing you to hear what is normal. Yours is probably the same thing, but without more info we can't tell. Turbo's make noise. The freer the intake is, the more you can hear it.
Do you have any way to monitor the boost pressure? There is a blow off valve that will kick in at 20 something psi. If you are building that much boost it may be opening up. Anyway, you can get a sending unit OBD2 kit that links to a phone app that will monitor a lot of engine parameters, and even do testing for you. The app Torque is a nice "gauge" set, while Forscan is a great diagnostic. Forscan home page has a list of appropriate sending units available so you buy the right one.
I think the system starts defueling at 29 psi and will throw a code that goes away after boost goes down. If you have a leak in a boot you might also get that odd sound. You can easily build a leak detector to pressurize the system and listen for leaks. Here is one that you can buy, but I made one from a 4"pvc cap, a gauge, a schraeder valve, and a clamp. 3" Dieselsite Turbo Boost Leak Detector
Another thought, if you can record the sound it might help us figure it out.
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