RPM/noise increase during the first few seconds of driving

I've noticed that when I first start driving for the day (or after several hours) my engine seems to rev up a little bit for a few seconds usually at 5-10 mph when I'm leaving my driveway. It's almost as if the engine is "working harder" briefly, but there isn't any surge in power or power loss really. It's more like excessive noise then it goes away.

is this normal? It does it with and without an idle warm up. I'm guessing this is some sort of cycle the truck is running when it first goes in drive. Has anyone else experienced this?

2021 TRD 4WD, 55,000 miles.

 

Following. Have the same thing happen. To me it sounds like a radiator fan kick on in a high setting if that makes any sense. It only occurs upon initially driving from a cold start.

 

It's the mechanical fan clutch. They all do it after cold start as you rev up the engine initially.

 

Normal!

 

All vehicles do this and always have.

 

Thanks all! My 2nd Gen didn’t do that (or at least not as noticeably).

 

This ^^^

The fan is hydro-mechanical and has a default to high when cold or failed. Once it is at operating temperature it reduces rpm until such time as it senses an over temperature and will ramp up as needed. This means it will be a bit noisier when you cold start the vehicle. If it doesn't do it, then you may have a fan clutch issue that needs to be addressed.

 

Thanks!