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Discussion Starter · #1 ·
This is not a Taurus, but I posted here to get max attention.

96 F150 5.0 engine.

Had codes 0171, 0174, 1131, and 1133 (not sure on the last two, didn;t write them down.) Anyway, I changed both front o2 sensors, mainly due to mileage. All of those codes cleared upon doing that, and I was presented with 0172. Thought I may have gotten a bad sensor, so I swapped it for the one after the cat, thinking the code would change if it were indeed a bad sensor. Same code after the swap.

Seeing the code says Bank 1 rich, I looked at the tip of the sensor and it was greyish-white, not black that a rich condition would cause.

FF data follows...

0 MPH 165 deg. F 44.3% Load 1027 RPM
STFT1 14.8% LTFT1 -16.1%
STFT2 10.9% LTFT2 -7.5%
STFT3 28.9% LTFT3 47.6%
STFT4 75.0% LTFT4 78.9%

Advice?
 

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What are the trims with the engine fully warm (190 approx.)?
 

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Discussion Starter · #4 ·
My scanner doesn't have RT data, just FF data. Has a new thermostat, but that was incidental.
 

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You can monitor the voltage output at the PCM connector to see if it is cycling. Should be oscillating between ~.2v to .8v
 

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Discussion Starter · #6 ·
CEL lamp is blown, don't know how long it was running 171/174 before I started working on it. Noticed very poor mileage and black smoke on heavy throttle, led me to seeing lean codes. That's why the sensors were changed in the first place. Forgot to disconnect battery to reset long-term trim values (I think they persist even when clearing codes with the scanner). Will drive it a few days and see if 172 comes back, and trim data at that time.
 
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