I have an 08 tahoe with two significant engine noises: When vehicle goes into v4 mode it has a pinging noise coming from the engine. I also have the high pitched noise which I can hear almost all of the time especially at highway speeds.

 

Welcome to the Tahoe forum. If no one here has any ideas for you, I'd recommend taking it in to dealer. It is still under warranty isn't it? That way you have a record of it.

 

Here is a recent link that may pertain to some of the sounds you are hearing

https://chevroletforum.com/m_83478/tm.htm

 

Sorry for not getting back-Thanks for the link. I have taken this to the dealer several times for the high pitch noise. They were doing some research on it before tearing into the engine. As far as the other noise when it automatically shifts from V8/V4 it sounds like an idler pully going bad. I will leave that up to the dealer this week.

 

Thanks for the Update, its the return feedback that makes this forum work!

 

Have you driven another NBS Tahoe to hear what the V4 mode sounds like? It's hard to describe but I liken it to a muffled Jake brake sound.