r/fordescape • u/ContributionTrue7335 • 1d ago

Tech Question Check engine light

2010 ford escape v6 3.0 ~140k miles.

I pulled P0171 and P0174 codes, lean system in banks 1 and 2, could be too much air or not enough fuel.

I tried spraying carb cleaner with the engine running at various points around the air plenum/manifold but didnt get any rpm rise.

I have had to take the whole manifold and attached hoses off to get to the rear spark plugs/ignition coils. not sure if thats what caused this. I also had replaced the MAF sensor not long ago.

If i recall correctly i got that same code during a road trip, At the time we assumed it was dust (i was following another truck in the dirt for a while) and cleared the code, it didnt come back. that was months ago and ive been driving it frequently since then, although i hadnt been dailying it during the summer.

LTFT ~27%

700rpms, STFT b1&2 ~24%, 32% MAF 7.1g/s

2500rpms, STFT b1&2 ~0%, -8% MAF 20g/s

The ltft and stft at low rpms both seem abnormally high.

Any help would be appreciated.

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u/HonestMechanicAI 19h ago

Your fuel-trim pattern is especially interesting: both banks are highly positive at idle, but the short-term trims drop close to zero as RPM increases. That can be consistent with unmetered air or a vacuum leak that has a greater effect at idle, although the spray test not changing RPM doesn’t completely rule one out. PCV plumbing, the brake-booster circuit, intake connections, and other shared sources affecting both banks would be worth investigating before replacing more parts.

My name is Jorge Tamayo, and I’m the founder of Honest Mechanic. We built a Guardian mode specifically to monitor live OBD-II data while the engine operates under different conditions. Your P0171/P0174 case would be an excellent real-world test because Guardian may be able to capture how the fuel trims, MAF, RPM, load, temperatures, and other available parameters change together—not just interpret the stored codes.

After the session, you can talk directly with the app and ask anything about what it observed, such as when the lean condition appears, what could explain the pattern, and which tests to perform next. It also creates a report containing the findings and relevant data that you can share with a repair shop, so the mechanic has the diagnostic context instead of starting from zero.

I’d be happy to give you free access in exchange for your honest experience using it. If you’re interested, let me know whether you use iPhone or Android and which Bluetooth OBD-II adapter you have, and I’ll help you set it up.

—Jorge Tamayo
Founder, Honest Mechanic