New TN User
Join Date: Feb 2019
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Slowly falling gas mileage
217K miles on 06 V6 4wd. Well maintained, engine and trans run great, brakes are well maintained. In fact, overall the vehicle is in great shape considering the duty it's pulled, so I'm inclined to put a little effort into helping it up to really high miles.
Gas mileage seems to be falling, very slowly. About 10% poorer last year or two in gentle driving, worse than that if I am more aggressive on the pedal. The two upstream O2 sensors are original, and in my mind becoming suspect simply due to age. One downstream sensor changed out about a month ago (P0158, high voltage), no other codes.
I hate to change out $112 parts in the blind. Is there a way to test the A/F system using Torque or Techstream? I have not yet used either of these... will have Torque running in a day or two, wouldn't mind getting some input on Techstream. Guessing the good deals to be had on ebay are all Chinese pirates? Malware issues, anyone?
Anyhow, if anyone has a minute, throw me a bone please, it won't go wasted. I'm a process engineer, live and breathe control systems for things other than cars, did a bunch of amateur tuning and logging on 3 different WRXs a few years ago with great success. TIA.