Bigger than normal MPG drop?
 

Has anyone else noticed a bigger than normal hit to mpg? I typically get around 24 in winter and now I'm getting about 22. I normally wouldn't be concerned but i have 6, soon to be 7 consecutive tanks below average. My route doesn't change, 56 miles straight highway with no traffic except the last 5 miles.

I got a new battery and set of tires right before the decrease, 3k miles ago. One half of the engine injects about 10% more fuel than the other, but it has been that way since i got the car.

Anybody else seeing lower than normal fe?


Edit: looking back at '14/15 i see that my mileage is in line... perhaps last year was more mild than i thought. But this year has been rather mild also... idk.

It's been pretty mild in my area as well. I wonder if your ECM "relearned" something incorrectly after the battery was reconnected. Those 6 or 7 tanks have all been since then, right?

Being a software nerd, I can't help but wonder if disconnecting the power and trying again might clear it up. ;)

My guess is that it is the tires.

Another vote for the tires.

A tire data point: The local rural mail delivery guy has a Prius. His mileage drops 3-4 MPG when he puts his winter tires on.

Temperature could be part of it. My truck mileage changes almost exactly 1 MPG for every 10 degrees F temperature change.

Update:

Since temps have come up a bit, but now gone back down, the last 3 tanks since 1-18-17 have been 24 to 25 mpg. Wich is pretty normal. I think the low mpg was probably to do with the weather. Though i also noticed the mpgs drop very quickly above 70, 2 to 4 mpg hit between 70 and 75. Cam phasing must be doing something around 2100 rpm.

3 tanks in less than 2 weeks? :eek:

Doubt it's anything to do with your cam. Speed kills for all of us. Do you need to be driving over 70 MPH?

Yes 3 tanks, i drive 57 miles each way to/from work.

Don't need to be, but sometimes i do. My thought is that as the drag increases, the throttle position gets to the point where the cam phasing starts to engage.

10% drop is reason for investigation. This rule was old when I first heard it in 1970s. Fuel and air filters first back then. Next was spark plugs and points. These were after tire related.

Its really odd, ever since i got the car it would ping with regular gas and then feel like a monster (for what it is) on premium. Now lately, the last couple months, it hasn't been pinging on regular and holds gear with much more throttle input.

I know there is something wrong since one side of the engine injects about 10% more fuel, the o2 sensors and cat temperature confirms this. But i dont know if it is the o2 sensors or the timing chain stretched.

I found out i have wideband o2 sensors stock, how do i view the afr?