====== 2006 Ford Expedition ======

This is Eric Songer's vehicle. I've helped trying to get the engine running a lot better. It runs weakly. 

  * Changed two of the three Oxygen sensors - little improvement, a few months ago [about 11/2025]
  * Today, replaced Fuel Filter - no improvement (MicroGard Fuel Filter - 33595, $24) [6/30/2026]

Today, saw these codes (saw 2 each of these 2, 4 total: 

  * P0171 - System too lean, Bank 1
  * P2197 - O2 Sensor Signal Biased, Stuck Lean Bank 2 Sensor 1

Looked at MAF, looked a little dirty, but didn't clean it.

Google AI says it could be Oxygen sensors, MAF, PCV, random vacuum leaks.

[6/30/2026]