Air releasing noise at startup

[Shift Happens]

I may be bad at searching but I couldn't find anything about this....anywhere.
Sometimes when I start the truck and start moving it makes a whooshing noise, or something that sounds like air escaping from the exterior of the truck. Can't tell where it's coming from but it's around the engine area.
I've not heard it on my in laws gasser JL, nor have I heard it on my diesel JL.

I'm going to dig through the owners manual in case it's mentioned in there as a normal function but wanted to see if anyone here knew of it, or what it might be.
2023 mojave

Might be the brake booster? Sometimes it just happens while moving(from initial start) and then goes away in a few seconds and doesn't come back. It will persist after full stop. Happens forwards or reverse. I can replicate pretty well if I go back and forth and hit the brakes but sometimes it happens without hitting the brakes at all. Lasts a few seconds, then stops regardless what I do.

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[Outback_Joe]

Sometimes mine makes a noise like that when the AC engages and charges the heat exchanger / evaporator. Turn off the AC and see if it stops. Sorry no other guesses.

Other than that your turbo wastegate is unloading.... Kidding!

 

[JTDay]

My 22 gasser makes the same noise with 28 thousand miles on it. I assumed it was just normal car noise.

 

[jeepers29]

My gasser makes that sound as well but usually after a big meal. Sorry, I couldn't resist.

 

[Dust]

x2. Mines a 2020 Rubi with 32k. Same deal!

 

[Not2Late]

I have not noticed it on mine, but now I will pay attention! I did have a Tundra that did something similar and was told by a tech that is normal and that it was the anti-lock braking system recalibrating on every start up. So maybe it's something like that?

 

[Klicht87]

I'm pretty sure it's the brake system/booster. Mine does it too, and I also notice it when I'm stop and go through a drive through after I press the brake.

 

[lo-fi]

My 2023 Mojave purchased this past Friday makes the same noise. I haven't had a chance to investigate. Didn't notice it somehow at the dealership.

 

[ShadowsPapa]

Could be the pump pulling vacuum in the brake booster..........

Antilock brakes typically do a self-test at 7 mph. (gotta be moving to check output from each sensor, etc. and it does this only one time per start cycle.

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