What is causing tire "chirp" sound when letting off the throttle?

[guitarguy]

I've only had my 2019 GT1 about a month, but I've noticed that when in Sport mode or Smart, after punching the throttle to the floor (for maybe 2-3 secs), when I let off the gas rapidly (because I'm doing 80 or more!) I hear a "chirp" sound. At first I thought it sounded like the rear tire(s)... isn't the tranny directly coupled to the drive train in Sport so the tires are reacting to the rapid loss in momentum? But now after listening further i'm not so sure. Never heard anything like that on any of my other cars, including my BMW 330. Has anyone else experienced this?

FWIW, it doesn't do it during acceleration or any other conditions, only what I described, when rapidly letting off the gas after rapid acceleration. Thanks for any insights!

 

[Ulikefishsticks]

Do you have Cold Air Intakes on? When I let off throttle rapidly, the BOV or something will make a higher pitch chirping sound as the air evacuates.

At least that is what I think is happening.

 

[MerlintheMad]

Do you have a squeaky kickdown switch? (I have no idea ...)

 

[guitarguy]

I'm guessing that cold air intakes are an aftermarket add-on? As far as I know I don't have those. I don't see anything connected to the intakes on the hood.

 

[Ulikefishsticks]

Get some audio/video of it and we can help a bit better.

 

[guitarguy]

Good idea I'll give it a try.

 

[guitarguy]

So I tried to upload but this site doesn't seem to allow video or audio... it says I have an "illegal file" (mp3). So here's a link to the audio file on Google Drive:
Stinger Chirp sound.mp3

For some reason it won't play directly on Drive but if you download it , it plays fine. In the beginning you hear it at 7 secs. in. However, it only did it the first time. Every time I tried to reproduce it, I didn't get that sound at all. I tried a couple more times on the recording, and after i stopped recording I tried a few more times, trying to exactly replicate how long I was accelerating and then letting off on the gas quickly, jsut like the first time on the recording. Nada. And come to think of it, every time it's happened in the past it was a single time, I don't think I ever tried multiple times in a row like I did just now. But every time in the past I punched it and let off like that, I got that sound. I'm stumped.

So that begs the question, what is it and why only on "the first time"? I'm starting to think it's the turbo and maybe the BOV? BTW the car was fully warmed up before I recorded or tried it, I never punch it unless it's been at operating temp for a while. Thanks for any help!

 

[Ulikefishsticks]

Yep, my car does the EXACT same thing. I don't think it's an issue. I think it's the turbo's dumping all their boost out the wastegate or BOV? I am not 100% sure on what is doing it, my car has been doing it since I have gotten intakes on over a year ago. Car runs and drives like a dream. Could also be a temperature thing. I never really gave it much attention to when it happens. Like you said, it only happens when you go heavy throttle and then dump it hard. Maybe someone can chime in and let us know what is actually happening.

It may be dependent on gear or RPM's when it gives that noise too.

 

[guitarguy]

That's good to hear you have the same experience. Thanks! Yeah, if any one has an idea of what's going on please let us know

 

[SoCalSHO]

That is the sound of blow off valves. It is louder with something like a K&N intake system.

 

[NS_Stinger]

So your car doesnt have any aftermarket mods like intakes or BOV's? The sound is normal in my opinion but it seems loud on your car if you dont have any mods. Did you buy your car new? Can you post a photo with your hood open so we can see?

 

[Stratofied]

I have noticed the same thing since putting on my Injen intakes. Most of the time even when driving hard, flooring it, releasing the gas pedal rapidly, and so on... it will make the normal pfffssshhtt sound, but every once in a while it just lets out this crazy loud chirp. I honestly thought maybe one of my hoses or couplers wasn't tight enough and was letting some air escape when the pressure is too high causing a chirp. Honestly just have no idea what causes it.

 

[GenesisG70]

Definitely intakes bot a deal at all.

 

[guitarguy]

Aha. Thought those were stock but after taking a look under the hood I definitely have Ingen intakes. Funny, I used to do a lot of my own engine repairs years ago, mostly simple stuff like carbs etc. but now I look at an engine and I have no idea what's in there.

I bought the car used from a dealer... makes me wonder what other mods the previous owner did. I'll have my mechanic take a look the next time I bring it in for service. Thanks for all the replies, that was really helpful!

 

[Kamauxx]

Other common mods are tuners and exhaust. Hard to tell if it's ever been tuned but you can post a pic of your exhaust and we'll be able to tell you if it's stock.

 

[guitarguy]

Great, I will do that. Do you need a pic of the exhaust pipes at the end or the manifold, or the entire system under the car? Thanks!

 

[Kamauxx]

Great, I will do that. Do you need a pic of the exhaust pipes at the end or the manifold, or the entire system under the car? Thanks!

If you can stick your hand under there and get a pic of the muffler that should be enough.

 

[NS_Stinger]

Aha. Thought those were stock but after taking a look under the hood I definitely have Ingen intakes. Funny, I used to do a lot of my own engine repairs years ago, mostly simple stuff like carbs etc. but now I look at an engine and I have no idea what's in there.

I bought the car used from a dealer... makes me wonder what other mods the previous owner did. I'll have my mechanic take a look the next time I bring it in for service. Thanks for all the replies, that was really helpful!

That explains it, the noises you're hearing are totally normal with those intakes on. The good news is I don't see any old adhesive marks on your fuse box on the top left, old adhesive marks from velcro would usually mean someone had a JB4 tuner installed.