Turbo Like Sound When Under Load

[Whiplash Willy]

I have been noticing that when I am accelerating and putting a medium or higher load on the engine I can hear a sound that is similar to what a turbo would sound like, just lower pitched. This happens whether my 4nr is up to temp or not.

I am wondering if is normal or not, and if anyone knows what this noise is.

From my understanding, the 2013s got the Air Injection Pump, that the V8 Tundras and 4th Gen 4NRs have had for while now. From my understanding though I believe the Air Injection Pump only runs until your vehicle is up to temp, but maybe it also runs under heavy load to help with emissions? It seems to me that it could possibly be that, but I don't know.

It really doesn't bother me, I am more just wondering if it is normal, and curious as to what it is.

 

[Stifler]

if you have a t4r.org sticker on your rig this is normal!:hat:

aside from that cant help you... mine sounds more like a diesel under load

 

[bimrunner]

Yes. I have this too and believe it is exactly what you described. I do get a big boost from my sticker though.

 

[<<<<]

That is normal. Thanks to electronic trottle your imput is indirect and you might have delay, but once compressor is on you're making power. Clear as mud. Hope it helps.

 

[diverscale]

Got the same sound under load with windows down. I would describe it as a very small turbo spooling. Normal behavior on our vehicle, even made a post about it when I got the truck, after dismantling the entire intake tubing to search for the cause.

 

[Clarkson!]

Turbo spool when revving down

Has anyone heard a slight whistling or spooling sound when revving the engine and letting the revs drop? I tend to hear a little whistle/spooling noise when the revs drop below 2k-1500rpm after revving to 4kish....wondering if this is exhaust leaking g from a cracked exhaust manifold as it's almost like a 1 to 2 second burst of noise as the rpms drop. Thanks.