P0171 Chevrolet -

Question

2007 Chev Silverado.
Had the truck into the dealer twice and they can not determine the cause for the lean code. The repair facility "was" a Chevrolet dealer until two years ago when GM downsized. The mechanics are the originals and have all but factory assistance as far as credentials. Is there a problem that may be inherit to this truck or this system especially with todays gasoline quality?
Do you have any suggestions?
Technician at last visit preformed multiple diagnostic tests, tested extensively for vacuum leaks and removed fuel rails to inspect fuel injector screens. Possibly a MAF?
He believes the fuel quality may be the problem. Testing while running, the engine appears to lean under acceleration just barely to trigger the engine service light. Any suggestions or assistance would be appreciated. I have written GM as I feel they should offer assistance, especially since I purchased this vehicle new from the dealer I am working with. As of this date GM has not answered my emails.
Thanks,
Ron

Answer 1

P0171 Fuel trim lean Bank 1

P0174 Fuel trim lean Bank 2

There alot of various factor that can set a lean condition for both sides of the Bank, Being lean you can experience long cranking times, hesitations, a light or intermittent misfire condition,  , If there are fuel injector resitriction it can cause the engine to operate at a lean air to fuel ratio. Try using a fuel injector cleaner that is added into the fuel tank,Which ever brand fuel injector cleaner you  use Follow  their instruction for the fuel injector cleaner you decide to use.