What's that sound?

Springtime · 01-13-2006, 12:23 PM

I have been driving my Prius for about a week. Today I noticed an odd sound. Hard to describe, but, sounds like blowing air through a cardboard tube of a roll of paper towels (I told you it was hard to describe!)

This sound occurs at low speeds maybe 10 - 15 miles per hour. I know the absence of sound means the Prius is using electric and at higher speeds it is using gas and I am wondering if this sound occurs in transition from electric to gas?

I almost thought I had left a window slightly open and I was getting some sort of vibrating sound - but, all windows were closed completely.

I get a little nervous when I here a sound I can't identify because when I bought my Tercel in 94 I kept getting an unusual sound at about 55 miles per hour. It turned out to be the windshield had a bad seal and at certain speeds it caused a high pitched sound when the air hit the windshield. I ended up putting my tape recorder in the car and taping the sound because it only happened occasionally. Once the service techs could "hear" the sound they tracked down the problem.

My guess is since I only seem to notice this odd sound at low speeds it may have something to do with the transition from electric to gas. I am just suprised I had not noticed it prior to today. Can anyone confirm this?

Springtime

tumbleweed · 01-13-2006, 12:33 PM

I try to listen to things too, sometimes helps find problems before it's to late as with your windshield. I don't think I have never heard the sound you describe. Could it be related to the brakes? Can you hear it if you start the engine while stopped, just pust the throttle down while in park and it will start. Could it be related to the heater blower, try turning the fan off.

mouztrpd · 01-13-2006, 02:45 PM

Could be the the pump filling the thermos when the ICE shuts down....I'm not sure if it does this whenever the ICE goes on/off or only with power on/off but I hear something similar whenever mine goes into stealth mode or maybe it's just my imagination

Mystery Squid · 01-13-2006, 03:47 PM

I know where you're coming from, as I've heard/hear it too. Made me think one of my windows was slightly open as well. I THINK it's general wind noise, eminating from the "front" of the doors where they seal up to the body.

Next time you hear it, try grasping your driver's door, and pulling it in, you should hear a change in the noise.

Bill Merchant · 01-13-2006, 04:09 PM

First, it's very hard to tell by sound, once the ICE has initially started, when the Prius shifts from electric to gas, the Energy screen is a better indicator and it does it all the time. Second, at low speed, wind noise is unlikely to be a factor, unless the wind is really blowing and you're headed into it.

I think this new noise is perhaps tire noise when the car is using the motors, motor/inverter noise when the motors are running, regenerative braking noise when the motors are producing electricity and the inverter is sending it back to the HV battery, or mechanical braking noise.

You didn't say, Springtime, whether you hear this noise accelerating, braking, or gliding. That could help pin-point the source. While the electrical system doesn't make as much noise as the ICE, it makes some, and it's unusual to hear in a car.

Springtime · 01-13-2006, 04:31 PM

Quote:

Originally posted by Bill Merchant@Jan 13 2006, 05:09 PM
First, it's very hard to tell by sound, once the ICE has initially started, when the Prius shifts from electric to gas, the Energy screen is a better indicator and it does it all the time. Second, at low speed, wind noise is unlikely to be a factor, unless the wind is really blowing and you're headed into it.

I think this new noise is perhaps tire noise when the car is using the motors, motor/inverter noise when the motors are running, regenerative braking noise when the motors are producing electricity and the inverter is sending it back to the HV battery, or mechanical braking noise.

You didn't say, Springtime, whether you hear this noise accelerating, braking, or gliding. That could help pin-point the source. While the electrical system doesn't make as much noise as the ICE, it makes some, and it's unusual to hear in a car.

[snapback]189412[/snapback]

Bill,

I first noticed it when I was accelerating at a very slow rate ( going from 0 to 25 mph on a side street). I heard the noise between 10 - 15 mph, by the time I got up to normal driving speed it was gone. I will pay more attention if it happens again and post further details.

Springtime

Jack 06 · 01-13-2006, 06:54 PM

Sounds like a low-speed, new-tire noise to me.

01-13-2006, 12:23 PM	#1
Springtime Senior Member Join Date: Nov 2005 Location: Eastern PA Posts: 144 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I have been driving my Prius for about a week. Today I noticed an odd sound. Hard to describe, but, sounds like blowing air through a cardboard tube of a roll of paper towels (I told you it was hard to describe!) This sound occurs at low speeds maybe 10 - 15 miles per hour. I know the absence of sound means the Prius is using electric and at higher speeds it is using gas and I am wondering if this sound occurs in transition from electric to gas? I almost thought I had left a window slightly open and I was getting some sort of vibrating sound - but, all windows were closed completely. I get a little nervous when I here a sound I can't identify because when I bought my Tercel in 94 I kept getting an unusual sound at about 55 miles per hour. It turned out to be the windshield had a bad seal and at certain speeds it caused a high pitched sound when the air hit the windshield. I ended up putting my tape recorder in the car and taping the sound because it only happened occasionally. Once the service techs could "hear" the sound they tracked down the problem. My guess is since I only seem to notice this odd sound at low speeds it may have something to do with the transition from electric to gas. I am just suprised I had not noticed it prior to today. Can anyone confirm this? Springtime __________________ Springtime Eastern PA 2005 Silver pkg #6

01-13-2006, 04:09 PM	#5
Bill Merchant absit invidia Join Date: May 2005 Location: USA \| Oregon \| Portland area \| 97004 \| Posts: 3,949 My Car: 2007 Prius Package: #5 Nominated 6 Times in 1 Post TOTM Awards: 1 Friends: 49	First, it's very hard to tell by sound, once the ICE has initially started, when the Prius shifts from electric to gas, the Energy screen is a better indicator and it does it all the time. Second, at low speed, wind noise is unlikely to be a factor, unless the wind is really blowing and you're headed into it. I think this new noise is perhaps tire noise when the car is using the motors, motor/inverter noise when the motors are running, regenerative braking noise when the motors are producing electricity and the inverter is sending it back to the HV battery, or mechanical braking noise. You didn't say, Springtime, whether you hear this noise accelerating, braking, or gliding. That could help pin-point the source. While the electrical system doesn't make as much noise as the ICE, it makes some, and it's unusual to hear in a car. __________________ Bill Bill.Merchant@PortlandHSD.info 2007 NL 5 Silver Wraith 2005 BC 6 Silver Cloud Portland Area HSD Meetup Group: PortlandHSD.info Become carbon neutral: Carbonfund.org or TerraPass.com

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01-13-2006, 12:33 PM	#2
tumbleweed Senior Member Join Date: Oct 2005 Location: Eastern Oregon Posts: 1,005 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I try to listen to things too, sometimes helps find problems before it's to late as with your windshield. I don't think I have never heard the sound you describe. Could it be related to the brakes? Can you hear it if you start the engine while stopped, just pust the throttle down while in park and it will start. Could it be related to the heater blower, try turning the fan off.

01-13-2006, 02:45 PM	#3
mouztrpd Member Join Date: Apr 2005 Location: Ogden, Utah Posts: 78 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Could be the the pump filling the thermos when the ICE shuts down....I'm not sure if it does this whenever the ICE goes on/off or only with power on/off but I hear something similar whenever mine goes into stealth mode or maybe it's just my imagination

01-13-2006, 03:47 PM	#4
Mystery Squid Junior Member Join Date: May 2005 Posts: 3 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I know where you're coming from, as I've heard/hear it too. Made me think one of my windows was slightly open as well. I THINK it's general wind noise, eminating from the "front" of the doors where they seal up to the body. Next time you hear it, try grasping your driver's door, and pulling it in, you should hear a change in the noise.

01-13-2006, 06:54 PM	#7
Jack 06 Join Date: Oct 2005 Location: Winters, CA: Prius capital of US. 30 miles W of Sacramento Posts: 2,567 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Sounds like a low-speed, new-tire noise to me.