I have replaced the port seals, isolater bolts, cleaned the EGR ports, plugs and wires, and chanced the air filter. I was getting both 171 and 174 codes. Now after 60 miles or so, pulled the codes again and am just getting the 171 code (Fuel trim bank one condition) any suggestions ? I was told that I may have to go to a dealer and have the comp re-flashed. Any help would be appreciated......

SOURCE: codes #171 & 174

first check out for o2 sensor if its faulty this can show up.but if its proper.Evaporative emission control system leak very small 171 System too lean (bank 1) 174 System too lean (bank 2) 

SOURCE: 1998 FORD EXPLORER SPORT 4X2 4.0 OHV

I have 98 explorer im getting same codes ive worked on cars all my life I havent replaced anything but my fuel filter so far on the explorer and that wasnt it.I know people tell you to replace all that other stuff,but if you know cars and how the stuff works thats on a car then you can fix anything with out people telling you;you need to buy this and then this and there just fishing when the dont know there as* and whole in the ground.Im going to replace my lower and upper intake seals like he says above.At least theres one more smart one out there and not someone that thinks they know it all like people that work in the parts places and some dealers.

SOURCE: codes 171 and 174 2001 ford winstar

dont take soo much in consideration after you have make all this things, some time is on only for any wire faulty, or a shrt electrical arc in any place in wire system. ask auto tap mechsnics for this maybe they have similar case before.

SOURCE: i am having a problem with a 2001 ford windstar.

Two bad O2 sensors is rare. The problem is before the sensor,intake vacuum leak, injector lower o-ring, IMCR stuck open or the control rod is off, vacuum hose(s) off, or MAF sensor. If this has a plastic upper intake, they had problems with o-rings.

SOURCE: check engine light on computer codes 171 174

switch, we run off snitches. 171 174 banks 1 & 2 Lean. Most likely cause are Upper Intake Manifold Gaskets, failed seals. It's not 1990 on. It's 1996 and on OBD2.