Change in gas mileage

[Slegacy96]

Ok, I consistently get 32 mpg hwy in my EJ25 Legacy. However, this trip I got 27, the vehicles EPA rating. This was the first official calculation I had done with my weapon-R short ram. I had switched from a K & N Panel filter.

Now here's the difference. I filled up with 89 octane rather than 87. The EJ25 debuted in 1996 and required 89 or higher. That changed in '97. But I figured I would give my Legacy some of the good stuff. Do you think it was the octane that made the difference? A nasty head wind, that I didnt notice? Or does anyone's gas mileage suffer when they go higher than 80 mph?

 

I really do think that it was the change in octane, but Im lookin for ideas that I hadnt thought of.

[nipper]

Ok, I consistently get 32 mpg hwy in my EJ25 Legacy. However, this trip I got 27, the vehicles EPA rating. This was the first official calculation I had done with my weapon-R short ram. I had switched from a K & N Panel filter.

Now here's the difference. I filled up with 89 octane rather than 87. The EJ25 debuted in 1996 and required 89 or higher. That changed in '97. But I figured I would give my Legacy some of the good stuff. Do you think it was the octane that made the difference? A nasty head wind, that I didnt notice? Or does anyone's gas mileage suffer when they go higher than 80 mph?

 

I really do think that it was the change in octane, but Im lookin for ideas that I hadnt thought of.

 

Winter fuel, tired o2 sensor. Gas Mileage doesnt really count untill you have 3 tanks of gas recorded.

 

nipper

[Slegacy96]

Winter fuel, tired o2 sensor. Gas Mileage doesnt really count untill you have 3 tanks of gas recorded.

 

nipper

 

I agree, however I make the drive from home to Penn State pretty often and always get 32 mpg. So winter fuel doesnt add up entirely. O2 senor might.

[johnceggleston]

do you always drive over 80 mph?? i find it hard to believe you get 32 mpg @ 80mph.

[fishy]

I notice that you said this was your first calculation with a new intake on. I wonder if you were craving the sound of an open intake a little and stepping into the loud pedal more than you normally would have? or maybe the ecu is learning the new ammount of airflow and over-fueling?

[Suzam]

I just did a run in our MY02 OBW from Delaware to Ohio via the PA turnpike.

 

The way out I cruised at 80+ MPH with the RPMs at 3000-3200 and got 24 MPG.

On the way back I slowed it down to 70-75 with the RPMs at 2600-2800 and shot up to 28 MPG, it took me and hour longer to get home.

[Slegacy96]

I notice that you said this was your first calculation with a new intake on. I wonder if you were craving the sound of an open intake a little and stepping into the loud pedal more than you normally would have? or maybe the ecu is learning the new ammount of airflow and over-fueling?

 

Very good point. I do enjoy hearing it, but I usually save it for the curvey roads.

Ive had the intake on for a while, and have never calculated it before, but this was the worst hwy mileage I have ever gotten with it. I know this because my trip required an extra gallon and a half of fuel.