IAS5

Have a '15, and am hearing an odd noise under a very specific condition. I can reproduce the noise at will at 40 mph, and maybe it happens at other speeds at the same rpm, but road noise is probably masking it at those higher speeds ---

- driving the car at 40mph, steady state.
- in 7th gear- I actually put it in M7 just to keep it in gear, but it can be in auto and it will still make the same noise
- while keeping it at 40, I take my foot off the gas ever so slightly--- you all know how slight the pressure on the pedal must be to keep it at speed--
- I, very gently, touch the accelerator for literally between 1-2 seconds- basically just to keep speed at 40- kind of like keeping the car between 39-40.
- as I take my foot off the gas, I hear this sound that almost sounds like some kind of turbo pressure release, since these turbos spool so quickly. Do we have some type of dump valve? Has anyone else heard this? It almost sounds like some moaning blowback.

If you try to replicate this, obviously have the radio off, and have the HVAC fan down low, or off. There are several times I have music on, and some of the roads traveling home are 35 and 40 mph, with some minor hills and crests. If I am on cruise at 40, any slight acceleration the car utilizes to manage the small hills to keep the car at 40 will produce the same sound when it lets off the gas as it reverses the hill.

All other factors have been ruled out-
- tire noise, as it it seems to be boost related, and at a certain rpm range 1300-1500
- it happens on any road surface
- any ambient temperature
- any vehicle operating temperature
- normal or sport mode

Thanks,

Steve