Funny sound shortly after takeoff

Don't confuse my curiosity of "what is this sound" with a complaint or concern.

I can confirm my car will make this sound in neutral; in sample run car went from park to neutral with no time in drive. Speed was 13mph. Not sure if this tells us anything, does it rule out the drivetrain in any way?

Next test I want to do is take off but keep it below 10mph for as long as possible (should be easy on side street) to see if it is speed vs distance dependent. I would also love to try this in reverse but my wife thinks it's a terrible idea

 

I can report that at least for me the sound is not a function of the distance or time, just speed. Today I managed to keep it below 13 miles per hour for two turns out of the garage and the noise (clank) occurred as soon as I hit 13 miles per hour.

Again it only seems to happen one time per startup, so I don't think it is a steering or suspension issue either. I guess if I was going to do one more experiment I might drive far enough to make the noise pull over stop the car start it back up and see if I can make it make the noise again immediately.

I don't have scheduled service for quite some time again now but if I can keep this in my memory I'll try to ask if they have any idea. But I'm definitely not worried about it in any way.

 

Mine is at the dealership right now for this issue along with a dash rattle. Will let the thread know what they say. I suspect it’s something to do with the gas tank pressurization.

 

Same here. Curious!

 

It happens on my Gen 4, Three Touring, like clockwork. My guess: it is the grill shutters closing. From where I sit, the sound comes from the front of the car.

 

They couldn't replicate the noise as it happens only once if you haven't started the car for a while, and if you miss it then you won't get another chance to hear it for a while.

I heard the noise much more clearly driving out of a parking structure today, and I don't think it comes from the gas tank anymore. It's coming from underneath the car. It just sounds like something springing into place, and only occurs around ~13mph.

The noise rattle came from a loose navigation antenna. According to the notes, they just added more insulation rather than nudging it into place. I didn't get a chance to talk to the tech, so I don't really understand how this isn't a problem for every Prius Prime Plus if the solution was to add more foam.

 

I had this exact issue on my 2006 Yaris. I described it to 2 Toyota technicians as a chirp or ping which only happened at every takeoff at a very slow takeoff speed after a few feet.
Each technician stood on one side of my Yaris and heard the ping for about 10 demonstrations.
They could never locate the source and track it down, so it was inconclusive to them.
Problem solved itself after I bought a new car. (New owner inherited the issue).

 

Googling for Toyota 13mph noise led me to Tundra forums claiming it is an abs check.

http://www.tundratalk.net/forums/#/topics/76134?page=1

 

This is my best effort to record the sound: 2017 Prius Prime Klunk

Bob Wilson

 

Page 167 of the manual discusses a speed linked door locking function which happens at 12 miles per hour. This is a setup function that you can change that will lock the doors when you shift into D, and is documented on page 750. Hope that helps.

Posted via the PriusChat mobile app.

 

Good call!

I'll check to see if pre-locking the doors makes a change. However, it is consistent with the observed symptoms down to the speed:

• once with each powered on operation
• 12 mph is close enough to the 13 mph

I am used to a louder sound when the doors lock but this is a very quiet car.

Bob Wilson

 

I think it might be the brake check. I have my locks set to lock when I shift out of P.

 

I am familiar with that sound but now I'm wondering if after going into "D" while not moving I can unlock all the doors. If they lock at 12-13 mph, there will be a distinct sound.

Bob Wilson

 

The clunk noise is nothing but the EBS activating. I had my first experience back in 2003 when I bought a 98 Saturn SL2. There was a distinct clunk sound when the car first reached over 8 to 10 mph. One of my office co-worker knew exactly what it was as he worked on cars a lot.

The EBS - Electronic Braking System activates once the car starts to go beyond 10 to 12 mph. Different companies have it set between 8 to 13 mph.

I heard it in my 2005 Highlander, 2012 Prius plug-in, 2014 Avalon Hybrid and now in my 2017 Prius Prime.

 

I never heard this noise in my 2007 Prius. I still believe it’s something to due with the fuel tank as it is coming from the rear left corner.