Weird Vibration/Buzzing at specific RPM and throttle

3.4 V6 - in a 2000 Tacoma, California Spec exhaust

The sound is pretty hard to describe, but it's very obvious. Even my mother pointed it out with a "what the hell was that?". But it happens in every gear somewhere around 1700 and 2050 rpm at medium throttle. It's the most obvious when there is some more load on the truck - say I'm going up a hill and trying to accelerate. Now here is where it get's a little bit weird, when your're light on the throttle it does not happen at all. When heavy on the throttle it seems dependent on the engine load if it wants to appear or not.

I ran some seafoam through the intake which fixed what seafoam usually fixes. Pulled off the connection for the TPS sensor. In the past 6 months I cleaned the throttle bottle, MAF sensor, and I have confirmed that the O2 sensors are functioning correctly. The only thing I'm thinking it could be, and I have no idea how to check this is that there is a baffle in the exhaust that is vibrating when the correct amount of exhaust gases are moving past it.

Anyone else have any ideas?

 

maybe this: https://www.youtube.com/watch?v=KINqlTNxajQ

 

Nope, not that. I went for a look around today and there is a rattle in my muffler and a seam is broken. I guess it's time for a replacement anyways. But I'm not so convinced. I guess time will tell.

 

well the heat shields on cats and the exhaust are famous for making these strange sounds so I would look there if the muffler doesn't solve it and if you are doing the muffler replace that donut gasket in the video because as you can see it can leak and im sure yours has never ever been replaced so I bet its time

 

Still haven't sorted this problem out...

I'm at an ends here. I have a shim under the rear leaf pack so pinion angles are fine. Could it be the carrier bearing or a bad u joint?

 

I would check carrier bearing and u-joints...I'm having a very similar problem in my 1998 I shimmed My hanger bearing down 1/2 inch and helped alot I'm gonna change it along with my u-joints this weekend I'm lifted 2" in the rear

 

Please let me know how that goes for you. I have my rear axel rotated with a shim due to my lift but assumed that this would have sorted any issues. I have a feeling both the u joints and carrier are original at 130k miles now. Did you buy a spacer or just use some washers to drop the carrier?

 

I'm assuming the noise is there when in park or neutral? If so have someone rev the engine to that rpm range and go looking. Mine makes this rattle sound around the same rpm range. I still haven't tracked it down but I'm beginning to suspect my manifold. Any codes?

 

It's a 5 speed actually and it will Rev smoothly with no load on the engine. It doesn't even happen if I accelerate slowly through the range.

 

I used washers I may drop it another 1/2 as that should get it close to factory