Fuel in northeast this winter

[Paul1963]

I’ve been pulling my hair out trying to figure out why my 2007 XC90 4.4L is using so much Fuel.
A few guys I’ve talked to say That this year the winter mix may have been even less effective a fuel and so gasoline this winter may even be worse than in past years and it could very well be that it’s just that the gas is absolute shit this year and that’s why I’ve lost my mileage
I did have a 171 and 174 code but it only popped up once and then the light went off.
However about 85,000 miles ago when the balance shaft bearing was replaced the so-called Volvo technician at the Volvo dealership had it all apart and put it all back together so I thought OK it’s time for a new PCV valve the hose that goes from that to the manifold and the crossover hose that goes from one valve cover to the other to all be replaced.
I bought all Volvo parts for this job including the Plenum gaskets when I got in there I found he didn’t put the clamps back on the hose for the PCV valve so those two clamps were gone that hose was hard but not cracked although it could’ve been leaking air because the oil residue was right down to the very end of the hose but no oil had dripped out that I could see.
the crossover hose from one valve cover to the other had a crack in it about an inch long at one end.
just beyond the nipple so there could’ve been a slightVacuum leak there however the best part about what I found was he didn’t clean up the intake and the Plenum at all.
I’m not so sure he didn’t reuse the gaskets because they’re so nasty I can’t imagine they were new when they were replaced it looks as though air was getting by those gaskets into the intake ports so this explains my 171 and 174 codes I believe.

The engine always ran pretty good despite this but now it runs even better it’s very smooth runs beautifully however taking it for a long road test the other day I’m still getting terrible mileage but The car runs crisper it even shifts nicer it’s overall better than it was in the engine in the transmission of always run very well but now they run extremely well.
I have no lift and I also have Lyme disease which makes it very difficult to get under the car the arthritis from limes disease is very debilitating so checking for a possible small vacuum leak in my eve app system is my next guess to go look at

However I wish to ask anyone and everyone here if they’ve run into this problem or what do you think it may be and maybe it is just that this year’s gas in northeast USA is that bad that my mileage would be so terrible even though again the car runs beautiful
anyone out there have any ideas?

[Masscomguru]

What is your current mileage and what are your current driving habits (around town, long highway trips, idling to warm up, ect)

[Paul1963]

It is true that I haven’t really gone anywhere all winter and I have been driving just around town and very close to home like 3 miles in and then back again so I’m thinking it was the winter fuel mix
I recently did the PVC system and found things I didn’t like from the last mechanic (Volvo tech) that was in there like for instance the two clamps that are supposed to go on the hose from the PCV valve to the manifold weren’t there the hose was just stuck on and left that way
also because they get hard they can crack, now the one from the PCV was not but the one that crosses between the two valve covers was and the crack went from the end of it just beyond the nipple so it was leaking just a little bit of air there and then the Plenum gaskets were so nasty I’m not sure the guy didn’t reuse them when he put the thing back together and those showed evidence of air leaking
So overall I think I just need to take it on a good long run and see if my mileage comes back

After getting the car’s engine back together it runs much smoother although it always ran pretty good but now it’s really super smooth and my fuel trims are much much better now although before they were high they weren’t extremely high but they were up there, now they’re down nice and low like they should be