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2001 Ford Escape V6 3.0L P0171 and P0174 Code: Rough Idle and Stalling Diagnosis

Model: Ford Escape Fault Code: P0171 Posted: 2008-03-30 03:19

I own a 2001 Ford Escape with a 3.0-liter V6 engine that is experiencing rough idling and occasional stalling. The vehicle seems to be underperforming despite having already cleaned the Mass Air Flow (MAF) sensor and replaced the fuel filter. I'm now looking for further troubleshooting steps to resolve these issues, especially since the check engine light has been triggered with codes P0171 and P0174 indicating lean air-fuel mixture in both banks.

Related fault codes
P0171P0174
Comments (3)
Anonymous 2008-03-30 09:58

Inspect for vacuum leaks, particularly in the PCV system and associated hoses. Even small leaks—such as a 1mm hole (about the size of a pinhead)—can trigger P0171 and P0-174 due to unmetered air entering the engine. Check all vacuum lines and connections for cracks or disconnections. Good luck, and please update if you find any fixes.

Anonymous 2008-04-01 16:30

Also verify fuel pressure levels, inspect for a weak fuel pump, EGR valve malfunction, or exhaust leaks before the upstream oxygen sensor. A purge valve leak in the evaporative emissions system can also cause lean conditions—especially when the charcoal canister is 'clean'. Any component allowing unmetered air intake or causing fuel restriction will lead to these codes. Older 3.0L V6 Ford Escapes are known for intake port gasket leaks. Be sure to examine all vacuum hoses and connections thoroughly. Touch wood... my 3.0L Vulcan engine has over 300,000 km and hasn't shown this issue yet! Hope I'm not tempting fate. —Aeroman

Anonymous 2012-01-15 16:01

This post may be too late for the original owner, but it could help others. My 2001 Ford Escape V6 had the same P0171/P0174 symptoms. I sprayed carburetor cleaner around all vacuum lines and at the base of the intake manifold one by one. When I heard a noticeable change in idle stability, I knew I found the leak. In my daughter's 2001 Escape, it turned out to be faulty intake manifold gaskets—a repair that takes about three hours and costs roughly $10 to fix.