Escaping/ Compressed Air Noise - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

DaBoBo21 · 02-06-2018, 11:53 AM

Hey guys. I wanted to revisit this. I've been looking to figure this out for months now and haven't been able to find anything. Since about late October I've been hearing a noise like compressed or escaping air whenever I'm in motion. Also, when shifting above 3.5K RPM you can hear a blow off valve or release of air type noise. Funny, because the car is completely stock and has no turbo. I've checked the intake and even went as far as deleting the sound tube to see if it made a difference, and it did not. No exhaust leaks either..

Bad vacuum line, maybe? Maybe drivetrain related?

ermax · 02-06-2018, 12:15 PM

Quote:

Originally Posted by DaBoBo21

Hey guys. I wanted to revisit this. I've been looking to figure this out for months now and haven't been able to find anything. Since about late October I've been hearing a noise like compressed or escaping air whenever I'm in motion. Also, when shifting above 3.5K RPM you can hear a blow off valve or release of air type noise. Funny, because the car is completely stock and has no turbo. I've checked the intake and even went as far as deleting the sound tube to see if it made a difference, and it did not. No exhaust leaks either..

Bad vacuum line, maybe? Maybe drivetrain related?

Auto?

DaBoBo21 · 02-06-2018, 01:53 PM

Quote:

Originally Posted by ermax

Auto?

MT. 13,700 miles on the odometer.

arren123 · 02-06-2018, 02:01 PM

Quote:

Originally Posted by DaBoBo21

MT. 13,700 miles on the odometer.

I hear it in my 2017 BRZ MT. It's totally stock.
I can only hear the noise when loading the engine, not at steady state.

I had my rear seats down and it sounds like it coming from the rear of the car, so I was thinking it was from the exhaust.

Try driving with your rear seats down and see if the noise is more pronounced.

DaBoBo21 · 02-06-2018, 02:04 PM

Quote:

Originally Posted by arren123

I hear it in my 2017 BRZ MT. It's totally stock.
I can only hear the noise when loading the engine, not at steady state.

I had my rear seats down and it sounds like it coming from the rear of the car, so I was thinking it was from the exhaust.

Try driving with your rear seats down and see if the noise is more pronounced.

Interesting. My noise is definitely coming from the front of the car. I hear it when it's steady and at WOT.

supercommode · 02-06-2018, 04:33 PM

Quote:

Originally Posted by DaBoBo21

Interesting. My noise is definitely coming from the front of the car. I hear it when it's steady and at WOT.

I hear the same noise from the front of the car, but I noticed it after I installed headers. It happens at WOT and when I rev it. I don't hear it at idle. I also have removed the sound generator tube. At first I thought it was a install problem with the headers and I had a leak, but after a rather lengthy inspection I couldn't find any exhaust leaks.

DaBoBo21 · 02-06-2018, 04:35 PM

Quote:

Originally Posted by supercommode

I hear the same noise from the front of the car, but I noticed it after I installed headers. I also have removed the sound generator tube.

Do you happen to get a BOV noise when shifting around 3500-4000 RPM? Just curious..

humfrz · 02-06-2018, 07:06 PM

Quote:

Originally Posted by DaBoBo21

Hey guys. I wanted to revisit this. I've been looking to figure this out for months now and haven't been able to find anything. Since about late October I've been hearing a noise like compressed or escaping air whenever I'm in motion. Also, when shifting above 3.5K RPM you can hear a blow off valve or release of air type noise. Funny, because the car is completely stock and has no turbo. I've checked the intake and even went as far as deleting the sound tube to see if it made a difference, and it did not. No exhaust leaks either..

Bad vacuum line, maybe? Maybe drivetrain related?

If it were a vacuum leak, I would think the engine would tell you via a code.

I can't imagine the driveline making a sound like that .....

I might suggest you re-check the intake for a lose clamp, lose hose, split hose or something else wonky.

Maybe your NOS is leaking ......

humfrz

ermax · 02-06-2018, 07:16 PM

I have an air like sound under load but that’s because I have a leak between my header and over pipe. Took a while to isolate it but it looks as if the flange is bent a little. Spray it with soap and it bubbles on the bottom end of the flange and you can see a gap at the bottom of this flange.

I’ve never noticed a BOV sound on shifts. The only sound I’ve noticed on shifts was a little ingnition knock (sounded more like a click) when doing very quick shifts were I would go back to the throttle very quickly and aggressively. I wouldn’t describe the sound as a BOVish sound though. I solved this problem by taking the transient ignition retard table from the 2017 rom and applying it to my 2013 rom. The 2017 TIR table pulls a lot more timing on transients then past roms. The sound is gone now.

DaBoBo21 · 02-06-2018, 08:43 PM

Quote:

Originally Posted by ermax

I have an air like sound under load but that’s because I have a leak between my header and over pipe. Took a while to isolate it but it looks as if the flange is bent a little. Spray it with soap and it bubbles on the bottom end of the flange and you can see a gap at the bottom of this flange.

I’ve never noticed a BOV sound on shifts. The only sound I’ve noticed on shifts was a little ingnition knock (sounded more like a click) when doing very quick shifts were I would go back to the throttle very quickly and aggressively. I wouldn’t describe the sound as a BOVish sound though. I solved this problem by taking the transient ignition retard table from the 2017 rom and applying it to my 2013 rom. The 2017 TIR table pulls a lot more timing on transients then past roms. The sound is gone now.

Sounds good. I’ll give that a check this weekend. @humfrz I’ll double check the clamps on the intake, maybe I overlooked it.

Yeah, I don’t usually hear the knock these things have, I do know what you’re talking about though. It really is a head scratcher, though. It’s like compressed air being released when I shift above 3.5k.

supercommode · 02-06-2018, 10:13 PM

Quote:

Originally Posted by DaBoBo21

Do you happen to get a BOV noise when shifting around 3500-4000 RPM? Just curious..

No, I don't hear anything like a BOV. At this point, I have no idea what it could be.

FRSBRZGT86FAN · 02-06-2018, 11:31 PM

Quote:

Originally Posted by supercommode

I hear the same noise from the front of the car, but I noticed it after I installed headers. It happens at WOT and when I rev it. I don't hear it at idle. I also have removed the sound generator tube. At first I thought it was a install problem with the headers and I had a leak, but after a rather lengthy inspection I couldn't find any exhaust leaks.

Quote:

Originally Posted by supercommode

No, I don't hear anything like a BOV. At this point, I have no idea what it could be.

Could also be the "whooshing" that happens with thinner wall headers.

Jajanken86 · 02-07-2018, 03:26 AM

I've noticed a similar sound when I installed my k n air filter

Sent from my iDroid

ermax · 02-07-2018, 06:24 AM

I farted once when shifting.

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02-06-2018, 07:16 PM	#9
ermax Senior Member Join Date: Sep 2017 Drives: 2022 BRZ Limited Silver Location: Jacksonville, FL Posts: 2,532 Thanks: 882 Thanked 2,045 Times in 1,188 Posts Mentioned: 68 Post(s) Tagged: 0 Thread(s)	I have an air like sound under load but that’s because I have a leak between my header and over pipe. Took a while to isolate it but it looks as if the flange is bent a little. Spray it with soap and it bubbles on the bottom end of the flange and you can see a gap at the bottom of this flange. I’ve never noticed a BOV sound on shifts. The only sound I’ve noticed on shifts was a little ingnition knock (sounded more like a click) when doing very quick shifts were I would go back to the throttle very quickly and aggressively. I wouldn’t describe the sound as a BOVish sound though. I solved this problem by taking the transient ignition retard table from the 2017 rom and applying it to my 2013 rom. The 2017 TIR table pulls a lot more timing on transients then past roms. The sound is gone now.

02-07-2018, 03:26 AM	#13
Jajanken86 Senior Member Join Date: Apr 2016 Drives: Silver FR-S Location: Saipan ✈ Portland Posts: 231 Thanks: 92 Thanked 36 Times in 28 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	I've noticed a similar sound when I installed my k n air filter Sent from my iDroid

02-07-2018, 06:24 AM	#14
ermax Senior Member Join Date: Sep 2017 Drives: 2022 BRZ Limited Silver Location: Jacksonville, FL Posts: 2,532 Thanks: 882 Thanked 2,045 Times in 1,188 Posts Mentioned: 68 Post(s) Tagged: 0 Thread(s)	I farted once when shifting.

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