Turbo noise & RPM

[brclark80]

2016 Civic EX-T, 30k miles.

I'm going 55 down a hill before making a right turn. I slow down to around 10 mph while taking the turn, then quickly accelerate to 45 mph. Once I let off the accelerator, the turbo whines for around 5-6 seconds while the RPMs hover around 3k during the same time then slowly going down to normal.

This happens a lot while driving with similar conditions. It's very predictable and has been doing this for months, but not before then. I also notice that the turbo sound is a lot more prominent while driving 35-45 mph.

Is this something I should worry about or is this normal?

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[BarracksSi]

You sure it's the turbo and not the CVT?

 

[sonicBOOMgray]

You sure it's the turbo and not the CVT?

This drivertrain is almost whisper quiet or library quiet with some irrelevant humming of whisper that is tolerable. I'm an acoustics engineer hence the nomenclature.

 

[invader]

2016 Civic EX-T, 30k miles.

I'm going 55 down a hill before making a right turn. I slow down to around 10 mph while taking the turn, then quickly accelerate to 45 mph. Once I let off the accelerator, the turbo whines for around 5-6 seconds while the RPMs hover around 3k during the same time then slowly going down to normal.

This happens a lot while driving with similar conditions. It's very predictable and has been doing this for months, but not before then. I also notice that the turbo sound is a lot more prominent while driving 35-45 mph.

Is this something I should worry about or is this normal?

Which grade and what ethanol content of gasoline are you burning?

https://www.pure-gas.org/index.jsp?stateprov=NC

 

[brclark80]

Which grade and what ethanol content of gasoline are you burning?

https://www.pure-gas.org/index.jsp?stateprov=NC

87 with up to 10% ethanol.

 

[brclark80]

You sure it's the turbo and not the CVT?

I don't know enough about CVTs or turbos to tell you the difference, I just always assumed it was the turbo. It may very well be the CVT. I've never driven a CVT before this car. How do you tell the difference?

 

[invader]

Give it some 91 or 89 ethanol-free once you run your tank as low as possible. It will definitely run better and more efficiently... Let us know how it turns out.

https://www.pure-gas.org/index.jsp?stateprov=NC

 

[BarracksSi]

I don't know enough about CVTs or turbos to tell you the difference, I just always assumed it was the turbo. It may very well be the CVT. I've never driven a CVT before this car. How do you tell the difference?

A turbo sounds like a very high-speed fan -- but it's nearly inaudible on our cars. You'll hear it better on big dump trucks; it goes "fssssssssss".

The CVT would "whine" if you hear it at all.

 

[fjrman]

Engine braking is a bit strange with a CVT. When I go down a steep hill the CVT will change to a "lower gear" and the engine speed will go up quite a bit.

Maybe the engine offers more braking when it's turning faster! Compressing more air per unit time.

Definitely different than engine braking with a manual transmission.

 

[sonicBOOMgray]

I don't know enough about CVTs or turbos to tell you the difference, I just always assumed it was the turbo. It may very well be the CVT. I've never driven a CVT before this car. How do you tell the difference?

One way to tell is look at your boost guage and keep an eye on it. If it doesn't light up, it isn't the turbo.

 

[brclark80]

One way to tell is look at your boost guage and keep an eye on it. If it doesn't light up, it isn't the turbo.

I drive with the boost gauge on most of the time. It does light up when I press the gas lightly, but it seems to be the CVT. You never stop learning I guess

 

[brclark80]

A turbo sounds like a very high-speed fan -- but it's nearly inaudible on our cars. You'll hear it better on big dump trucks; it goes "fssssssssss".

The CVT would "whine" if you hear it at all.

I've watched a couple videos of CVT whine on Youtube, and it sounds nothing like those. It's like a high pitched whistle that goes up in pitch when I hit the gas or accelerate, then fades down to nothing. I would liken it to the noise a big turbo diesel truck makes when accelerating. Can you link me to an example of a non turbo CVT making this noise?

Very similar to this noise, though doesn't sound so much like a toy?

 

[brclark80]

Give it some 91 or 89 ethanol-free once you run your tank as low as possible. It will definitely run better and more efficiently... Let us know how it turns out.

https://www.pure-gas.org/index.jsp?stateprov=NC

I'll try that on my next tank, thanks for the link!

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