Anyone have any good ideas on where to start with two system codes? I have an 03 Sub w/the 5.3l with about 80K on it.
P0171System Too Lean (Bank 1)
P0174System Too Lean (Bank 2)
I am just not sure where to start. Just curious if anyone has any good ideas or clues where i can start wrangling this dragon. It is a Z coded motor (E85 compatible) which I just dumped two or three tanks in on a trip from WI to CA. Since then it has run like crap once I got back to CA. I have dumped some Fuel system cleaner and Octane boost in it, in this last tank, no luck. HELP? I am fairly knowledgeable but this is stumping me on where to start, any help would be great. Thanks,

JrBlaster
03 Sub
03 Bonneville

 

intake gaskets are leaking,gm sells an updated gasket

 

Thanks P. I will give that a try first. Thanks for the reply,

JB