Loud engine at 55mph

When I reach approx 55mph, my engine gets louder(like its struggling) and continues to about 70mph, then its fine. It kind of sounds like a hole in the muffler sort of, why only at this speed. Stronger noise when going up hill.

 

x2. i get this in my 11 too. hard to hear sometimes bc the rpms r fairly high at 70 mph. once i go into neutral to slow down it goes away

 

Why only at these speeds?

 

Likely something to do with harmonics at specific engine loads.

 

if u think about it, when do u have sustained rpm's this high other than cruising at 70 mph? manual and automatic 5 spd's alike, the only time ur gonna be at 3000+ rpm for an extended period of time is at these speeds

 

Lifted or stock height?

While accelerating, or letting off the gas?

Kind of a deep " big truck" noise?

Might be a driveline vibration rather than engine noise. My lifted 4banger does that.

 

Toyota dealer looked at that area and replaced some of it, and its still making the louder noise at 55. I think its stock lift and makes the noise while accelerating. Does your truck start making the noise at 55. Today I was testing out my 4H wheel drive and noticing my wheels locking up when taking slow corners, I wonder if that could be doing something!

 

Mine 2011 kind of acts that way too. It is always on the loud side but at certain speeds it gets REAL loud. I think that in addition to what somewhat mentioned about the noise level can be expected to change as the engine produces different amounts of power there might be certain frequencies that resonate in the cabin that make things loud.