Slight "hiss" when letting off accelerating past 4500 RPM - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Prax · 04-30-2017, 10:55 PM

Hello everyone!

The engine is finally broken in, oil is refreshed, everything is going great.

I noticed this small "hissing" noise that seems to sound like a really quiet mini blow-off valve every time I accelerate into 4500 RPM territory and let off the throttle. I haven't ventured passed 5k RPM or WOT yet, still slowly working it in.

This only seems to happen at 75%+ throttle.

Everything checks out, sensors are all good, vacuum sensor shows near zero on throttle (0.2). It seems like there is a very small, almost inaudible hissing sound coming from the engine bay at idle.

The car is practically new, and the vacuum/air/intake lines all seem to be where they should be.

Looking for any thoughts on what it might be.

Thank you!

humfrz · 05-01-2017, 01:10 AM

Hi ya, Prax ......

If I recall proper, this "hiss" has been heard before.

You may wish to do a search.

If you car is stock, I would bet that the "hiss" is just the intake quickly "gasping/blowing off" ....... nothing to worry about.

Just another weird sound this engine makes .....

humfrz

Prax · 05-01-2017, 01:13 AM

Quote:

Originally Posted by humfrz

Hi ya, Prax ......

If I recall proper, this "hiss" has been heard before.

ft86 forum hissing site:www.ft86club.com

If you car is stock, I would bet that the "hiss" is just the intake quickly "gasping" ....... nothing to worry about.

Just another weird sound this engine makes .....

humfrz

The car is very stock. It probably is normal, just a new sound I am not used to. Thank you for the info, I will probably just have to get used to it.

Sent from my Nexus 6 using Tapatalk

Ultramaroon · 05-01-2017, 01:21 AM

Just be careful when you open the hood.

Exrald · 05-02-2017, 12:08 PM

Quote:

Originally Posted by humfrz

Just another weird sound this engine makes .....

humfrz

Our engine is so loud! It's not even a "fast car" sound; more like the Engine is pushing hard as it can, to put a smile on our faces. lol

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humfrz · 05-02-2017, 12:26 PM

Quote:

Originally Posted by Exrald

Our engine is so loud! It's not even a "fast car" sound; more like the Engine is pushing hard as it can, to put a smile on our faces. lol

Sent from my SM-G920I using Tapatalk

Yep, sort of like an under powered tractor pulling a three bottom plow ......

Let's hear it from the old farm boys out there .......

humfrz

Jajanken86 · 05-02-2017, 06:54 PM

My hiss got a bit louder after dropping in a K&N air filter. I think it's normal

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WRBrzRX · 05-02-2017, 07:01 PM

Deleting the sound tube removes this.

Prax · 05-02-2017, 07:44 PM

Quote:

Originally Posted by WRBrzRX

Deleting the sound tube removes this.

I might have to delete the sound tube, really wish they wouldn't engineer useless things like that.

Sent from my Nexus 6 using Tapatalk

04-30-2017, 10:55 PM	#1
Prax Member Join Date: Jan 2017 Drives: 2017 BRZ Inazuma Edition Location: EDMONTON, AB, CANADA Posts: 42 Thanks: 29 Thanked 22 Times in 14 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Slight "hiss" when letting off accelerating past 4500 RPM Hello everyone! The engine is finally broken in, oil is refreshed, everything is going great. I noticed this small "hissing" noise that seems to sound like a really quiet mini blow-off valve every time I accelerate into 4500 RPM territory and let off the throttle. I haven't ventured passed 5k RPM or WOT yet, still slowly working it in. This only seems to happen at 75%+ throttle. Everything checks out, sensors are all good, vacuum sensor shows near zero on throttle (0.2). It seems like there is a very small, almost inaudible hissing sound coming from the engine bay at idle. The car is practically new, and the vacuum/air/intake lines all seem to be where they should be. Looking for any thoughts on what it might be. Thank you!

05-01-2017, 01:21 AM	#4
Ultramaroon not playing cards Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 32,395 Thanks: 53,053 Thanked 37,228 Times in 19,308 Posts Mentioned: 1117 Post(s) Tagged: 9 Thread(s)	Just be careful when you open the hood. __________________ service manuals

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05-01-2017, 01:10 AM	#2
humfrz Senior Member Join Date: May 2013 Drives: 2013 FR-S, white, MT Location: Puyallup, WA Posts: 30,432 Thanks: 29,826 Thanked 32,845 Times in 16,844 Posts Mentioned: 715 Post(s) Tagged: 2 Thread(s)	Hi ya, Prax ...... If I recall proper, this "hiss" has been heard before. You may wish to do a search. If you car is stock, I would bet that the "hiss" is just the intake quickly "gasping/blowing off" ....... nothing to worry about. Just another weird sound this engine makes ..... humfrz

05-02-2017, 06:54 PM	#7
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)	My hiss got a bit louder after dropping in a K&N air filter. I think it's normal Sent from my SAMSUNG-SM-G935A using Tapatalk

05-02-2017, 07:01 PM	#8
WRBrzRX Senior Member Join Date: Nov 2015 Drives: runs&drives Location: CA Posts: 123 Thanks: 304 Thanked 95 Times in 55 Posts Mentioned: 3 Post(s) Tagged: 1 Thread(s)	Deleting the sound tube removes this.

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