2003 Suburban Engine Knock

[Chevrolet9403]

I have an 03 suburban and it will knock on start up if I don't fill it with highest octane gas from Shell, Chevron, Or 76 Stations. The knock will last for a few days on start up, then go away. Does anyone have the same problem? Besides filling only at these stations, does anyone know if there is something I can repair to avoid this problem.

 

[zora]

Do you have a check engine light?

 

[VanGo]

Could be carbon buildup. I've had good luck with Seafoam intake treatments in the past. I'd look for codes first.

 

[cory0306]

My 01 tahoe did the same thing it turned out to be bad intake manifold gaskets
they are plastic omg install new metal ones once install knock quit also cold start s were fixed live in mn burr.

Hope it helps ya

 

[VanGo]

Do you have a check engine light?

That would be me first place to check. Newer vehicles have knock sensors. It could be mechanical like carbon or a vacuum leak, but I'd see what the computer says first. it doesn't cost anything.