Gas mileage

Splinter · Post by **Splinter** » Mon Mar 27, 2006 7:38 pm

I know this is a pretty interesting adventure for just about everyone. The kinds of mileage we get seem to range widely from 8 to 30mpg

Ive talked to a couple other local subaru owners (imprezas, legacys, gls) to get an idea of how they're fairing as well.

Based on what they've said, and my own observations, Ive come to the conclusions that our cars are basically insane.

I tried being a grandma for a few tanks and keeping it under 2500rpm, and I got a consistant 200 miles from full to empty on the gauge.
I tried keeping it around 3500rpm, with lots of snappy acceleration but no hard launches where I went right through any gears, and I got a consistant 200 miles from full to empty on the gauge.
Ive tried replacing PCV valves, and running them with breathers, Ive tried grounding mods, new plugs, new wires, new coilpack, dumped the muffler, opened up the intake, just about everything

The only thing that seems to affect my mileage is hard launches where I go right through gears. I dont even see how thats possible. How can driving at 3500rpm on boost use the same amount of gas as 2500rpm on negative pressure?

The only thing I have left to try is replacing the O2 sensor.

We've all seen these threads before where people talk about possible parts of the car that could be wonky and causing poor mileage, but what I would like to hear in this thread is what your driving style is like compared to your mileage. Where do you shift? Where do you cruise? etc

I'd really like to get this figured out

BAC5.2 · Post by **BAC5.2** » Mon Mar 27, 2006 7:41 pm

My on-highway, off-boost gas mileage improved when I got a 16G.

Negative pressure = vacuum...

I went from 20mpg in the Forester, to almost 23mpg by keeping it under 3,000 RPM. Worked like a charm.

I got a pretty consistant range in the Leg too. About 190-ish miles.

AWD_addict · Post by **AWD_addict** » Mon Mar 27, 2006 10:16 pm

Driving not too hard, so the 4EAT shifts are at about 3,000 RPM. Freeway on ramps get shifts about 5,000 RPM. Freeway cruise about 3,250 RPM.
This gets me about 20/28 mpg.

Bheinen74 · Post by **Bheinen74** » Mon Mar 27, 2006 10:25 pm

I noticed after moving back to IA from CO that my mileage is way down. I used to fill up at conoco or Amoco, but here in IA the local gas is Citgo. Also, i recently fixed the speedo gear in the tranny, and though maybe that is why my MPG dropped drastically (i used to get 30)
I have been getting about 17 to 18 with shitgo. But the last two tanks I have run Amoco Ultimate again, and am now getting around 2//23 again. No more Shitgo.
94 turbo wagon.

Manarius · Post by **Manarius** » Tue Mar 28, 2006 1:07 am

AWD_addict wrote:Driving not too hard, so the 4EAT shifts are at about 3,000 RPM. Freeway on ramps get shifts about 5,000 RPM. Freeway cruise about 3,250 RPM.
This gets me about 20/28 mpg.

You must not have AWD. I do the same as you and get 20-22.

thefultonhow · Post by **thefultonhow** » Tue Mar 28, 2006 4:26 am

Manarius, I think something is dragging your mileage down. I beat the crap out of my car (most of the time flooring it; shifting at or above 4000 rpm most of the time, etc.) and still get 19 mpg.

AWD_addict · Post by **AWD_addict** » Tue Mar 28, 2006 8:50 pm

Manarius wrote:You must not have AWD. I do the same as you and get 20-22.

<--Check my username

Manarius · Post by **Manarius** » Tue Mar 28, 2006 9:41 pm

thefultonhow wrote:Manarius, I think something is dragging your mileage down. I beat the crap out of my car (most of the time flooring it; shifting at or above 4000 rpm most of the time, etc.) and still get 19 mpg.

I should check those sensors my ECU threw codes for. I wonder if they could fix mpg being shitty...

thefultonhow · Post by **thefultonhow** » Tue Mar 28, 2006 9:47 pm

Manarius wrote:I should check those sensors my ECU threw codes for. I wonder if they could fix mpg being shitty...

Which sensors?

Generally there's something wrong if your ECU is throwing codes.

Splinter · Post by **Splinter** » Tue Mar 28, 2006 11:02 pm

I picked up a pair of honda single conductor O2 sensors yesterday for a pack of cigarettes

Lets see how they fair.

sammydafish · Post by **sammydafish** » Wed Mar 29, 2006 9:38 pm

Autos will be worse on milage than manuals. If you have a stick, the ECU shuts the injectors off completely when you're decelerating about about 1600-1800rpm, sogoing down hills and coming to stops you'll get better economy if you leave it in gear. I got 25-28mpg on my turboed Na 5spd AWD wagon.

If your miliage is bad, the biggest factor is driving style. After that, O2 sensor, temp sensor and low air in your tires are things that often kill miliage without giving other drastic affects. Of course worn plugs/wires bad injector spray (dirty) and other things will hurt economy too, but they often also result in serious loss of power and missfire.

Manarius · Post by **Manarius** » Wed Mar 29, 2006 11:00 pm

thefultonhow wrote:
Manarius wrote:I should check those sensors my ECU threw codes for. I wonder if they could fix mpg being shitty...
Which sensors?

Generally there's something wrong if your ECU is throwing codes.

It threw codes. It threw one for the O2 sensor, but I can't afford to like buy a new one of those. At least, not as far as I know. I also had one for knock and something else...it's in another thread.

jnorion · Post by **jnorion** » Thu Mar 30, 2006 6:34 am

I have FWD and the 4EAT... I do virtually all my driving through the city, half freeway and half surface streets. I mostly cruise at 1500-3000 for normal driving, but do some redline or close-to-redline runs on freeway ramps once or twice a day.

Average mileage including freeway and town is 24-25.

tahiti350 · Post by **tahiti350** » Thu Mar 30, 2006 8:31 pm

91 Legacy LS AWD, 4EAT, N/A, all stock, last fill up 290 miles 13.2 gallons, 21.969 mpg, back and forth to work, mostly stop and go, with a few miles of hiway. Last long hiway trip got 28 mpg with the rears alignment messed up (toed-out). Hoping for 30 plus on next trip.

I drive fairly aggressively, not crazy throttle to the floor, but I'm no granny either.

AND I suspect I have a problem with the temp sensor, due to hard cold starting problem. still need to scope it.

Tahiti350

Tone-us · Post by **Tone-us** » Fri Mar 31, 2006 9:23 pm

hmm that's weird.... I have a 92 NA AWD 5-speed, I just traveled down to southern Idaho from where I live.... about 300 miles away, On the way down I averaged 33mpg and on the way up 33.9mpg? of course this was all highway miles. On an everage 50% city driving and 50% highway I got 24mpg. Just all city I get about 19? weird isn't it!

MPtyza · Post by **MPtyza** » Mon Apr 03, 2006 1:46 am

Back when my Legacy was still turbo, I would constantly get 24 mpg until the IAC valve crapped out on me and I constantly got 13mpg. That's a mixture of city and highway miles.

Project_Legacy · Post by **Project_Legacy** » Mon Apr 03, 2006 7:46 pm

i do a lot of city driving and the mileage for my FWD auto non turbo'd legacy and the mileage for my AWD 5 speed turbo'd legacy seem VERY similar.

when i was using the auto FWD, i would beat on it most of the time. running shell or chevron most of the time and i would always pump more probly about when it was at an 1/8th. i usually got around 275? basically all city driving.

for my awd 5 speed turbo, i would usually shift at 2K to 3k RPM, almost never go into boost except under extreme circumstances and pumping gas at about the same time i would in the auto. i usually got around between 250 to 275 also. o yea as of right now, my turbo doesnt have an o2 sensor connected, and my IAC valve gets a little screwy. and remember, thats all city driving!

555BCTurbo · Post by **555BCTurbo** » Mon Apr 03, 2006 8:14 pm

Wow...and I thought my mileage was bad...

I am running a rising rate fuel pressure regulator, that makes me mega rich on boost...and I still get at least 340 miles to a tank...even with my "spirited driving style" (my car sees 0-90mph at least once every time I drive it)

SuperRallyRoo · Post by **SuperRallyRoo** » Fri Apr 07, 2006 7:11 am

340 miles to a tank holy crap!!!!!! I can't do that on the freeway in the tw ever. Man my rally car doesn't even go that far. 300 max in the rally car. Theres no way you can go 340 miles on 15.9 gallons of gas! The turbo wagon will go about 190 miles to a tank mostly city driving. The rally car will do about 240 city... 340 thats nuts, geo metro nuts...

Splinter · Post by **Splinter** » Fri Apr 07, 2006 7:12 am

Ive gone back to driving like I did when I first got the car (leadfoot accelerating) and my mileage hasnt changed.

Ive also disconnected my O2 sensor.

These cars make no sense.

206er · Post by **206er** » Fri Apr 07, 2006 10:36 pm

I usually get about 26mpg with half and half interstate cruising and flooring it around town.
the worst tank I have got with my current configuration is about 20mpg.
but jeezus, there is a mpg thread about once a month.

scuzzy · Post by **scuzzy** » Sat Apr 08, 2006 2:45 am

with my EJ22T sans the turbo, and EJ22 ECU, I see 20-22 in the city, depending on my style (worst ever was 19) and on the highway, depending on how hard or fast I drive, I can get up to 26-28

city: about 220 a tank
highway: 270+

I normally fill my tank when I've got about 3 gallons left (below a quarter tank)

Manarius · Post by **Manarius** » Sat Apr 08, 2006 4:01 am

Splinter wrote:Ive gone back to driving like I did when I first got the car (leadfoot accelerating) and my mileage hasnt changed.

Ive also disconnected my O2 sensor.

These cars make no sense.

How would one disconnect their O2 sensor? And what effect does that have?

Splinter · Post by **Splinter** » Sat Apr 08, 2006 4:20 am

The O2 connector is about 6 inches from the sensor, unclip it and the ECU has no idea how rich or lean its running

You should only do this if your O2 sensor is behaving badly

SuperRallyRoo · Post by **SuperRallyRoo** » Sat Apr 08, 2006 7:33 am

i got 8mpg when i ran without an o2... I could watch the gas gauge go down it sucked.

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Gas mileage

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