1997 Ford Explorer runs lean

1997 FORD EXPLORER
170,000 MILES • 6 CYL • 2WD • AUTOMATIC
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ERNEST8FINGERS
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My 97 Ford Explorer has the "check Engine" light on and I read the trouble codes- P0133/P0171/P0174 this is telling me that the "upstream O2 sensor(133) is malfunctioning and both banks of engine are running lean(171 & 174 both pending). Should I start with replacing O2 sensor? After clearing these 3 codes(w/o fix) I immediately get 2 codes(171 &174) w/o the O2 sensor(that takes another 40+ miles to show up). I hate these electric fuel pumps buried in the gas tank. I am starting to think its the fuel pump or maybe the fuel filter? Thanks in advance-Ernest
Mar 12, 2010 at 7:57 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,248 POSTS
It could be the sensors, but before replacing them, I would look for vacuum leaks. Many times a leak will cause a lean mixture.

Let me know what you find.

Joe

PS: If you are worried about the fuel pump or filter, check pressure at the fuel rail.
Mar 13, 2010 at 4:18 AM
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ERNEST8FINGERS
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It could be something as simple as a bad gas cap. I replaced the cap-cleared the codes and so far(maybe 100 miles) no light. Of course with 170000 miles it- just a matter of time before that "damm" light comes back on. I am poor and will run this truck(which has been a solid performer) till the flames force me out-lol.Thanks for the reply and advice .
Mar 13, 2010 at 5:05 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,248 POSTS
Let me know if it worked.
Mar 13, 2010 at 9:27 AM
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