1999 Ford Explorer, 4.0L OHV Engine - Vacuum Leak search. I think there is a vacuum leak in the upper intake plenum gasket. This leak is causing a Check Engine Light (CEL) code of P0171 (Bank 1 lean) and P0174 (Bank 2 lean). There are many reports of this type of Vacuum leak on the various Ford forums and some great how-to's on making this repair. Where is my leak??? This is me spraying carburetor cleaner all over the area of the upper intake gasket area and plenum (plastic).
1999 Ford Explorer, jlrohio