Air leak noise on cold start?

2018 TOYOTA LANDCRUISER
100,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
Avatar
2018LC200
  • MEMBER
  • 1 POST
When I first start my car in the morning, I hear a hissing noise for 10-20 seconds then a pressure release sound (please see video). In addition to this the acceleration power is reduced, shifting is not smooth, idle RPMs appear high compared to before, and I occasionally have engine shake when idling.

I have had the throttle body cleaned and programed based on mechanics recommendation which seemed to provide some temporary improvement however the problem returned the following day.
Video (Click to enlarge)
Attached Media
Feb 24, 2025 at 2:18 AM
Advertisement
Avatar
STRAILER
  • CERTIFIED EXPERT
  • 53,854 POSTS
Thanks for the video, this sounds like an air injection problem like the air switching valve is getting stuck, can you get a better idea of where the noise is coming from? I would remove the air switching valve and clean it to see if that helps, plus with the engine cover off you may be able to get a better idea of what is making the noise. We should run the codes as well, there might be something stored there.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the images (below). Please let us know what happens.
Images (Click to enlarge)
Attached Media
Attached Media
Feb 24, 2025 at 2:14 PM