Diminishing mpg?!

[Sonataman]

Since this past summer and 45k service, my fuel economy has been dropping, a lot.
Went from 44-45 mpg averages now down to 38 to 39 mpg and it has been a steady decline, not just since this cold weather had hit. Started after getting my 45 k service done when they disconnected the battery to clean the connections and terminals, they did not have corrosion.....

I thought after the car 're-learned' how to work again it would be fine but it has not come back.

The other indicator something is different is that my oil temp would run 10-20f higher so I was thinking I had a sticking caliper, still not sure, BUT my cat1 cat2 temps are running normal temps. Short and long term fuel trims are running where they normally do, -5% to -9%.

Is gas quality taking a major dump or what?

 

[CourierDriver]

take it back to the Einstein that worked on it ,imho .

 

[Barkleymut]

Why take it back? The guy may have already messed it up, why risk it again? It is really easy to find out if a caliper is sticking, go down a slight hill and put it in N. If it slows down then something in the braking system isn't right. I doubt disconnecting the battery would have much affect after a couple hundred miles. did you possibly get new tires? Did they rotate the tires?

 

[Brybo86]

Jack up each wheel with brakes off and spin them , they should spin many times before stopping

Have you used any fuel/injector cleaners recently? My FIL sonatas owners manual says if you aren't using top tier gas to use fuel treatment with each oil change

 

[147_Grain]

MPG can be lower while the ECU relearns things.

 

[Sonataman]

Thanks, have not used S1 in a while, but I only run 90 octane E0 in it.
Guess I should run a cleaner and see...

 

[The_Eric]

Originally Posted By: 147_Grain
MPG can be lower while the ECU relearns things.


How long do you expect him to wait?

Originally Posted By: Sonataman
Since this past summer



Adaptives shouldn't take more than a week or two with normal driving.