Rattling noise when accelerating

I think it’s the HPFP. Happens to me too. What are the chances that we all have rocks between the exhaust covers or that we all experience this at 40mph. I experienced a similar problem on another vehicle. When the engine didn’t get the proper pressure it would knock. Replaced pump and problem was solved.

 

My truck (2015 taco w/ 80K miles) has been making a funny sound only when accelerating and under 40mph. Been going on for about 2 months. I wouldn't say mine sounds like a rattle or metallic like people describe with the loose heat shields. Mine sounds garbled, almost like a boat engine under water sound if that makes sense at all? As I accelerate its like I can hear the normal engine sound but it's got like a repetitive bubbly waaahhhh tune to it. As soon as I let off the gas it stops. Over 40mph it goes away completely and sounds normal. Cold or hot it will do it on accelerating. Any thoughts on it being different than yalls? My wife and I have been having to switch cars frequently transporting kids and what not so I forget to check it out while driving hers, until I get back in the truck and notice it again.

Doesn't make the sound in neutral sitting in the driveway pressing on the gas. When it happens it feels like I hear it towards the engine bay a little to the right as I'm sitting in the drivers side.

 

Has anyone figured this out? It's driving me nuts.

 

Same issue, no solution yet. It happens on my wife’s 08 Highlander, too…

 

The "bubbly waaahhhh tune" that you're describing is a symptom that is nearly always caused by an exhaust link. Spray soapy water all over everything after the headers (or I guess they're built in, so maybe cats and after?) while it's running and look for bubbles.