Topic: Gas mileage... very bad (Read 1064 times)

pcsuby312 · « **on:** June 25, 2011, 04:17:47 PM »

So I've had my 2002 WRX on the road for about a week, and it seems to be getting very trashy gas mileage. I mean very bad. I took it to Crossgates and back from Chatham, plus a couple extra miles, and that in itself took a quarter of a tank. Driving the car very conservatively, I should be getting about twice that. I'm wondering, if the previous owner used only premium gas, if the ECU would adjust to that octane rating and then get worse gas mileage on lower octane gas, like regular gas? If so, switching to only using premium gas would make my gas mileage a little better possibly? Any help would be appreciated...

flutyr525 · « **Reply #1 on:** June 25, 2011, 04:34:43 PM »

you should be ONLY using premium gas. even on a stock wrx, it only should be fed 93 octane. also, when is the last time the fuel filter, air filter and spark plugs were replaced? how many miles are on it? my 2004 completely built heavily modded and tuned wrx gets ~20mpg and my 2002 stage 2 mildly modded and tuned wrx gets ~23mpg.

pcsuby312 · « **Reply #2 on:** June 25, 2011, 04:55:08 PM »

So if it was filled once with regular should I let it get to reserve before I fill it up with premium? Or should i get some sort of octane booster and do that to the remaining regular gas?

flutyr525 · « **Reply #3 on:** June 25, 2011, 05:43:23 PM »

if im not mistaken, there is no reserve in a wrx, or any car for that matter. i thought that was only motorcycles, ATVs, etc. i guess i wouldnt worry about it now that its done...just fill her up with 93 octane from now on

pcsuby312 · « **Reply #4 on:** June 25, 2011, 05:46:22 PM »

Alright then. Its 93 from now on. But is it possible that the bad gas mileage is a result of a confused ECU?

Trev · « **Reply #5 on:** June 25, 2011, 05:49:22 PM »

Actually some cars and trucks have reserve. I can go about 50 miles beyond E in the wagon before it starts to lose pressure and my truck has 5 gallons when the needle hits E.

pcsuby312 · « **Reply #6 on:** June 25, 2011, 06:00:58 PM »

What he said. Haha. By reserve I meant after the needle hits empty, at which point you still have a bit more gas.

Iant333 · « **Reply #7 on:** June 25, 2011, 06:29:08 PM »

Honestly unless you are driving like granny you aren't going to get much more than what you are though. My WRX swapped RS if I tried to baby it would get like ~28mpg and that was really going sloooow.

And yes, you will get significantly worse gas mileage on 87 than 93 since the ECU retards the timing a bunch making you waste gas.

Kavik · « **Reply #8 on:** June 25, 2011, 08:16:42 PM »

ALWAYS fill up with at least 91, higher if it's available.
If you think it's the ecu, it certainly couldn't hurt to disconnect your negative battery terminal, depress the brake for a few second, let it sit for a bit and reconnect...then drive the car for a good half hour in the way you want it to learn (conservatively or aggressively)

After that, track it for a few tanks. Fill it to full, reset the tripometer, drive it, fill it to full again and repeat. Use the tripometer mileage and the amount of gas needed each time to calculate the actual mileage...these gas gauges are no where near accurate enough to base it off what the needle says.

Then you can give us an actual number and we'll have a better chance of telling you if it's normal or if there are other things you should be looking at (like the things fluty mentioned)

p.s.
I believe the low gas warning light comes on when the car is down to 2 gallons, which for me on the 4 wrx's I've driven, has always been below the E for a ways before the light kicks on)

RedRoof2 · « **Reply #9 on:** June 25, 2011, 08:31:15 PM »

If your gas mileage is in the shitter, hook up a scantool or tactrix and take a peek at your Short and Long term fuel trims, your O2 sensor readouts and coolant temperature sensor data.

LarenF3D5 · « **Reply #10 on:** June 25, 2011, 09:45:56 PM »

I only get 17-20mpg on my Stage 2 tune.. But I also have a "gross evap leak" sooo...

evoWiPeR · « **Reply #11 on:** June 25, 2011, 10:04:17 PM »

Ya i can get 18-24mpg depending on how i drive. I agree with everyone 91+ only
Plugs and fuel filter, only cost like 50-75 bucks to change so i do them every 30k.

Do what Kavik said once you have refiled to ensure best driving conditions....

also on ur gas door, does it not premium unleaded fuel only

.. well mine does

pcsuby312 · « **Reply #12 on:** June 26, 2011, 12:04:25 AM »

It does say premium unleaded fuel only. Sometimes I get this thing where I read stuff and then completely disregard it. As in, I read that statement and then proceeded to fill up with regular. I'm usually a stickler for directions and ensuring that I'm doing things right, but that little statement just didn't phase me...

Kavik · « **Reply #13 on:** June 26, 2011, 12:29:25 AM »

well, for the sake of the car....follow this one. One of the joys of owning a turbo'd car, gotta pay the premiums (pun intended)

evoWiPeR · « **Reply #14 on:** June 26, 2011, 02:07:14 AM »

Quote from: pcsuby312 on June 26, 2011, 12:04:25 AM

It does say premium unleaded fuel only. Sometimes I get this thing where I read stuff and then completely disregard it. As in, I read that statement and then proceeded to fill up with regular. I'm usually a stickler for directions and ensuring that I'm doing things right, but that little statement just didn't phase me...

BlackParis · « **Reply #15 on:** June 26, 2011, 09:48:24 PM »

The dealer filled the forester with 87 when I picked it up.. GOt like 15mpgs... Since I switched to 93 It got almost 19mpg (heavy footed)

But its WAY BETTER than my camaro that got 7-8mpg thats the way i look at it.

Trev · « **Reply #16 on:** June 27, 2011, 01:57:07 PM »

Quote from: BlackParis on June 26, 2011, 09:48:24 PM

The dealer filled the forester with 87 when I picked it up.. GOt like 15mpgs... Since I switched to 93 It got almost 19mpg (heavy footed) But its WAY BETTER than my camaro that got 7-8mpg thats the way i look at it.

I went from a truck with 5 maybe 6 to the gallon, used to put 20 in, went to school for a week, back and forth, and would be below E... now if i put 20 in my wagon i can go to vt and back and still have half a tank....

madlife · « **Reply #17 on:** June 27, 2011, 03:31:45 PM »

I thought stock WRX only required 89 octane? {Mid}.

spoolordie · « **Reply #18 on:** June 27, 2011, 03:46:40 PM »

I thought it was 91+

Anywho i get 20-21MPG and thats 50/50 city/hwy plus dipping in to boost hard daily on a VF48

I only use 93 (Sunoco, Mobile, Hess)

20 BLK WRX 04 · « **Reply #19 on:** June 27, 2011, 06:18:52 PM »

once I bought 92 octane from the getty and my car got much worse mileage. always use 93

Kavik · « **Reply #20 on:** June 27, 2011, 06:23:29 PM »

that was probably more to do with the station than 1 octane rating off. I've bought 93 from different stations and had pretty drastic differences

Dreaded1 · « **Reply #21 on:** June 27, 2011, 06:33:43 PM »

I filled up with Stewart's 93 on Saturday then drove to Vermont and back on Sunday. I got an amazing 320 miles out of 11.2 gallons. Yes that was 28mpg at stage 2. I have only come close to hitting 300 miles on a full take a couple of times. I am wondering if I didnt really reset the odometer after I filled up. Even though it is a pretty simple operation, I swear I pushed the button. I have picture to prove the mileage and tank indicator. I used the Android app Torque to monitor the mpg while I Was driving and it was registering 28-29 mpg but I thought that was not correct until I filled up today.

Kavik · « **Reply #22 on:** June 27, 2011, 07:49:32 PM »

there's a thread buried somewhere from like a year ago where I was tracking mileage from different station......believe it or not, Stewarts has always gotten me the best mileage

(though, not close to that good

)

RedRex · « **Reply #23 on:** June 27, 2011, 07:52:43 PM »

Quote from: madlife on June 27, 2011, 03:31:45 PM

I thought stock WRX only required 89 octane? {Mid}.

Nope. You can use 91, if you can find it. I always used 93 in my '03 wrx. Around town, lead-footed or not, averaged 22+ mpg.

On a trip, cruising, 28.

JLyons013 · « **Reply #24 on:** June 28, 2011, 12:46:06 AM »

i wish i got 28mpg! i average 20mpg on my 06' NA(dont need premium

)..i thought id be doing much better then that though and most of my driving is higway

Author Topic: Gas mileage... very bad (Read 1064 times)