My 2016 Scat Pack Shaker is a whistlin' dixie and it's driving me absolutely bonkers. Car has ~12k miles on it. All stock under the hood, with Borla S-Type exhaust (w/ active exhaust valves) put on by the previous owner.
I posted about this once before when the car was new to me but now I've had a chance to properly dig a bit. I posted a few attempts at recording the whistle in the old thread, though the sound quality was pretty poor. Old thread:
A few details about the noise
* Whistle, I would describe it as reedy, high-pitched
* Occurs when the engine is under load (light throttle applied resulting in mild acceleration)
* Does not occur at a standstill. The car must be moving (hence the "under load" requirement). Revving the engine at a stop does not reproduce the noise.
* Confirmed in gears 2, 3, 4, 5, 6, 7
* Occurs over rpm range: ~1600 to 3000.
* Occurs at any speed so long as in the right rpm range and accelerating (under load)
* Does not change with engine speed, other than requiring the aforementioned rpm range for the sound to be present
* Occurs when the car is completely cold or after driving for hours
* Occurs for any outdoor temperature (from 15 F to 85 F)
* Sound occurs with active exhaust valves manually wired open
* Sound occurs with active exhaust valves manually wired closed
* Occurs in standard mode and sport mode
* When whistling in either standard or sport mode, pushing the Sport button makes the whistling stop (even with active exhaust valves wired completely open or completely closed). In other words, slightly different throttle input is required for making the noise in the two different modes
* This sound is different from the "whoosh" of air going into the CAI when I mash the accelerator
* This whistle occurs every single time I accelerate. It's always reproducible.
* I think it's coming from the front, though identifying sound location can be tricky
I disconnected the active exhaust valves and wired them open (notches at 2 and 8 o’clock position). Sound present and unchanged. I then wired the active exhaust valves closed (notches at 4 and 10 o’clock). Sound present and unchanged.
I'm heavily leaning toward the throttle body. In one of the zillion threads I've read, it was confidently stated that it's either the throttle body (specifically the butterfly valve within) or the bypass, and to just live with it.
* I removed the shaker assembly and air filter (so air comes through bare throttle body). The whistle is still present, and I believe it’s louder.
* I removed the throttle body and inspected the o-ring, which looked fine. I reattached the throttle body; whistle is still present.
* Torquing down the throttle body proved to be a bit troublesome. Even at 44 in-lb, once screw turned and turned, so I put EZ-lok inserts in. Torqued down, whistle still present.
* I tried taping around the seam where the throttle body interfaces with the intake manifold, but it's hard to say I got it 100%. Did not seem to make an effect; whistle still present.
At this point, I'm more and more convinced it's air whistling over the butterfly valve as it is pulled in to the throttle body. I'm ready to either purchased a larger throttle body or send my throttle body off to The Fastman, but I'll be doubly disappointed if I spend a few hundred bucks and still have the whistle.
I'm frustrated, and open to any thoughts or guidance you might have on this issue.