1998 V70 AWD OBDII Live Data check

[TheLoneAviator]

Vac lines fixed the High High STFT (Stuff hitting The Fan) reading. I think thats fixed now. figured out the boos gauge.

[regent]

Vac lines fixed the High High STFT (Stuff hitting The Fan) reading. I think thats fixed now. figured out the boos gauge.

Glad you got that one sorted. I understand, The Fan can now spin freely once the boos are adequately metered (gauged) Cheers!

[TheLoneAviator]

Everything SPINs fast'r wid a'lit'le Boos...

[TheLoneAviator]

Dadgummit, STFT S2 is still running approx 30'ish. I guess this is also my running rich & poor mileage problem. Still must be a vacuum leak somewhere.

[regent]

If, after fixing all vacuum leaks your gas mileage is still poor, remember that once you hit the 100 kmi mark, the HO2S are no longer as trustworthy as they used to be, so with 'the STFT rate' being that high, it will get stink at times (the exhaust that is)...

It is recommended to replace the oxygen sensors after 100kmi - and if you do, then this is also VERY important:
Reset the fuel trims so the computer relearns the new sensors much sooner.

Note that if you've just addressed a major air-to-fuel ratio problem (like vacuum leaks), even if you did not change any sensors, resetting the fuel trim matrices is a necessary (if not sufficient) step to getting your gas mileage back close enough.
Otherwise, the computer may take way too long to re-learn and re-adjust.
Please post back.
Cheers

[TheLoneAviator]

Thank you for that. I did replace the front O2, and reset the ECU, so it's re-learning from zero. Only got about 8 miles on it so far so not enuff to determine mileage. Computer average is within 0.5 of calculation. Looks like the rear o2 is a booger being on top of the pipe and no lift, my next house is gonna have a life out back. I figure the rear one needs replaced also, maybe this w/e.
Can you explain what effect the rear o2 has?

[regent]

On earlier MYs, the downstream sensor monitors the cat's performance only, so it does not have any bearing on gas mileage/efficiency. It is the upstream sensor that matters in your case - but as I can see, you are already two steps ahead...
On a car like yours, I would not worry about the downstream one unless it starts throwing codes at me.