2003 suburban 1500 5.3L surges on cold mornings (mid 20s and below). It also idles quite a bit higher than normal during this condition as if were an old carburetor rig. After it has been up to operating temp for a while this condition goes away. Codes give a multi cylinder misfire. Dealership thought intake gasket was possible cause. It has done this for a few years now during the winter months so I have my doubts about the intake gasket hypothesis. My instincts suggest it is an electrical component somewhere that wants to be in Arizona or somewhere warmer. Any thoughts?

 

Welcome to the forum. As the engine warms up, the metal tends to expand and perhaps the intake gasket is the correct diagnosis as the expanding metal could seal a small leak.

 

For me, here in AZ, this is an indication of dirty injectors. as they gum up etc they have a hard time adjusting to the ecm inputs etc.

So I usually throw in techron, 20 gallon bottle on a 1/4 tank x 2.


.02

 

I've done numerous intake gaskets for those symptoms, if you have access to a scanner you need to check the fuel trims while its cold and warmed up.

 

+ 2 for intake gaskets. +2 for viewing fuel trim at idle and 2500rpm. if its adding fuel at idle but comes back in spec at 2500 a vacuum leak is indicated.


leaking gaskets lean out the fuel mixture. when its cold, the mixture must be rich.

 

Thank you for your help everyone. They are all good advice. I will follow up and let you know what I find