Intermittent Howling Sound

I have a 2017 SR, Access Cab. I sometimes hear a howling sound when I back off the throttle with the engine turning 2000 to 2500 rpm. It is more likely to do it (or perhaps I am more likely to hear it) when the road is wet. It is not a terribly loud sound, although it can be clearly heard.

I have read the various threads on howling sounds and the sound I am observing does not seem to be the same as the sound/conditions described by others. Any thoughts/suggestions ?

 

Sounds like what I have going on. I'll see if I notice it more in the rain now. I was thinking it had something to do with cross wind... now I'm not sure.

 

I made a similar thread that I think died.....anyways. Mine happens on acceleration. Have you done the howling differential TSB? Reason I ask is a member there thinks the howling sound shows up in a different spot now that the springs and other stuff was changed out. I guess like the harmonics changed.

 

It might just be wind in the door channel. A couple members have added their own weatherstripping to the channel. Could be coincidental about your other hunches.

Where's it coming from?

 

I have the exact same issue. I've noticed right at 58mph when I let off of the gas. I thought it was the rear end so I took it to the dealership an they found no problems.

 

It's coming from under the truck. Can't tell location beyond that.

 

...and it doesn't always do it.

 

Same issue, but it happens so infrequently that I've yet to determine any rhyme or reason. Never stays for long either, so I havn't felt any reason to explore further.

 

It's cuz yooooooo haven't got a Ti knob...gosee!

 

?

 

Plus 1

^^^^????^^^

 

58mph has been the sweet spot for many members with the rear diff howl. Letting off the gas is when it does it the loudest for most. Did you mention the howl TSB to them? The TSB applies to your model. Then again correlation doesn’t imply causation or something like that ha

 

Is the howling addressed by the TSB a mechanical problem or simply an harmonics annoyance ?

 

I have just over 900mi on my new 2018 TRDOR DCSB, and I hear the howl pretty regularly. From what I've been able to tell, I believe it's coming from the blade in the throttle body. It seems to be manufactured in just a way that, within a certain speed/throttle position/rpm envelope, the air happens to pass through the throttle body/blade /just/ right to create the sound. Almost like blowing across a blade of grass between your thumbs to make it whistle.

I dunno... just my two pennies, but it's certainly not coming from underneath mine, and is pretty clearly coming from the engine bay. To me anyway it seems to be the only mechanically explainable thing to cause it. I'm certainly not sweating it or anything. Just kinda interesting I suppose. Never had a car do that before, haha.

 

Mine definitely changed. Instead of the 50mph-ish howl it now does it under acceleration... especially if I’m loaded down with passengers and / or gear. I’m dealing with it but when I’m loaded down I think I prefer how it use to be

 

I have not heard any howl when accelerating. Only've heard it when backing off the accelerator.
Where do I find the TSB addressing this ?
Thanks

 

Toyota was replacing diffs at first, but then realized it was just harmonics. The TSB adds a few things, but the harmonic dampers are what help the most. They just attach to rear cab mount.

 

https://www.tacomaworld.com/threads...oise-howling-when-feathering-throttle.442341/ or https://www.tacomaworld.com/threads/new-tsb-whine-noise-from-rear-of-vehicle.532809/ should have the TSB on the first page.

 

thank you

 

Brought the truck up to 58 mph and feathered the accelerator and she howled. Tried it again and no howl.

Even when the howl occurs it is not very loud. I think I can possibility live with it as long as: 1). it doesn't get louder, over time; 2). it is not a mechanical problem, just harmonics.

I am wondering how loud this howling has been for others.