Ej25 mpg

[LeggyxPower]

ok so this thread is going to be a little different, i have searched high and low.
So its winter here and i mainly do all city driving. Car runs fine no issues.
i have been averaging 14-16mpg. I don't have a heavy foot, i am more of a laided back driver.
But this just doesn't seem right, that modified wrx's are getting better mpg than my poor ej25d.

I don't have any cel's i have recently changed,
-pcv valve
-fuel filter
-air filter

Things next on my list to change
-Temp Sensor(i heard that could cause it)
-O2 Sensors
Both of the costly things :(

So fix anyone has encountered this and has a sure fix let me know, until now i will keep chasing it..Also post up your MPG

[meepers]

tire pressure, run some injector cleaner through as well.

I generally get around 17-20 in town, cold motor, short trips. On the highway it all depends on speed. 24-28 is good. but I have gotten 500 miles on multiple tanks with the cruise set when the tach hits 3100rpm (my cars sweet spot)

[Thomistopheles]

I was getting 26/28 with my old Outback in the winter, 28/30 in the summer. My EJ22E swapped LGT gets around 26-28 average. You should be getting at least 20 if not 22 city. I'd look at tire pressure, coolant temp sensor, plugs + wires + possibly coil pack if it's getting weak. Front O2 sensor as well, wouldn't worry about the rear since that one is more for monitoring cat efficiency than for air fuel ratios. If you ever smell raw fuel, check the filler neck and tank for leaks.

[rkrenicki]

Knock sensor is another possibility. I know I had a pretty big jump in MPG after changing mine on my old 96 Outback.

[lord flashheart]

On the last tank before I wrecked my car I was averaging 12mpgs. But those were special circumstances.


my grandpa was always telling me "you keed your goddamn foot out of the carburetor!"

[LeggyxPower]

Haha would I notice any of the symptoms like I said my car running fine plugs and wire were changed 50,000k ago from previous owner but I was going to do again either way...the car has 170k on it or 105k miles. My tire pressure is 40psi..I know I need to change my filler neck it's pretty rusted but no leaks. As for knock sensor would I notice if that's going out. And you guys are such an awesome crowd with good info vs other fourms


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[lord flashheart]

When was the last time you got an alignment? That's one of the large contributing factors on why my car got shitty mileage.

[LeggyxPower]

No idea lol , the wear on the tires is even and don't get any pulling


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[lord flashheart]

I would still have a shop check it, can't hurt, I send my car in every year even when I Dont notice anything there is usually adjustments that need to be made. You can also check to see if you got a brake drag from a sticky caliper or bad sliders/slider bushings. Have a tire shop do a comprehensive check.
Do a tune up. Beyond that the oxygen sensor is the next thing I would go after.

[LeggyxPower]

I think I will go after the front o2 sensor next,
All the brakes and sliders i checked over the summer after one of my calipers seized.So I will rule out brake drag. Knock sensor i will probably rule out as well, i don't seem to have any symptoms at all of a bad knock sensor.

Temperature sensor interests me, though my car hits temperature and stays there fine and after it warms up it idles at a normal RPM. and starts just fine when warm as well. Would there be any other symptoms?

I also should add i cleaned my MAF as well

[lord flashheart]

Well keep in mind you have 2 temp sensors one for the gauge and one for the ECU. If you have a scanner with live data you can check that.
The think about that is if your fans cycle its highly unlikely. The reason is because if your temp gauge was causing the fuel economy issues it would because it would be staying in open loop/start up enrichment. Which the computer goes close loop at 180 degrees F and the fans Dont cycle until 198 for the primary and 206 for the secondary.
If your confident all your brakes and suspension is good then a O2 sensor is the most likely culprit.

[Wiscon_Mark]

What's your average trip length with the in town mileage? If you're making short trips and not reaching closed fuel loop (operating temp has to be reached for a certain amount of time before you get efficient), those numbers could be realistic.

[LeggyxPower]

What's your average trip length with the in town mileage? If you're making short trips and not reaching closed fuel loop (operating temp has to be reached for a certain amount of time before you get efficient), those numbers could be realistic.
I forgot to mention that! my morning travel is 10 minutes(7km), yes the car does warm up by then , but not sure when it would hit a closed loop. I do that 5x a week and my afternoon travels are usually longer 20-30 minutes. i know that takes a toll on my mpg but that drastically? and winter gas.
But i used to do the same trips in my EJ22E and i always managed 20+mpg.(And i used to beat on it very often vs my ej25d)

[lord flashheart]

Was your 22 in the same car and you swapped it for a 25? Or did you get a different one, the 25 usually came in the gt and the 22 in the L, LS, and LSI.
The cars with the 22 were typically lighter, and narrower wheels, smaller brakes, different gear ratios, etc.
If you swapped it, it may just be the fact that your computer is mapped for a 2.2.
It would be an interesting experiment to see how a L with a 25D swapped in does on fuel economy vs a car with a factory 25D

[LeggyxPower]

Was your 22 in the same car and you swapped it for a 25? Or did you get a different one, the 25 usually came in the gt and the 22 in the L, LS, and LSI.
The cars with the 22 were typically lighter, and narrower wheels, smaller brakes, different gear ratios, etc.
If you swapped it, it may just be the fact that your computer is mapped for a 2.2.
It would be an interesting experiment to see how a L with a 25D swapped in does on fuel economy vs a car with a factory 25D

I have a 1997 legacy brighton with the ej22e but ran 195/60/15 on it vs the stock 185(tires).and it was a 5mt
My 1998 LGT Has the EJ25D on 205/55/16 with a 4EAT

[Bookem]

I have a 1997 legacy brighton with the ej22e but ran 195/60/15 on it vs the stock 185(tires).and it was a 5mt
My 1998 LGT Has the EJ25D on 205/55/16 with a 4EAT

That's your problem right there, lol!
But on the serious side, does the trans drag down the rpm down when you let off the throttle like a torque converter locked up all the time?
Also what kind of exhaust do you have? Maybe plugged cats???

[LeggyxPower]

That's your problem right there, lol!
But on the serious side, does the trans drag down the rpm down when you let off the throttle like a torque converter locked up all the time?
Also what kind of exhaust do you have? Maybe plugged cats???

Not 100% sure what you mean?
And i have a uel header and a vibrant muffler the rest is stock. I'm not showing any symptoms of a plugged cat. I read somewhere that its probably best if your installing a new header to replace the o2 i can't remember that persons reasoning.

[lord flashheart]

I like where he is going with the cat. When they get plugged it creates a lot of back pressure on the engine. Think of engines as a air pump, power is a bi-product. So if the engine has to work harder to move air, it has to work harder to create the power required to move the car. But the car would be be down on power especially in the top in if it was a cat. If they are plugged, you can make a cat glow from all the pressure and heat. I've seen it. I've seen fires start from plugged cats. I still would go for an 02 tho.

[LeggyxPower]

Agree because my car runs fine and exhaust doesn't glow. So it looks like I will be ordering up a denso O2.
I really appreciate everyone useful input


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[Wiscon_Mark]

I've noticed that closed fuel loop doesn't happen super quickly on my Forester after it gets up to temp (keep in mind that it's not actually at temp when the needle gets to its spot, it's probably around 160*F and operating temp is more like 180-190). I would say you're likely operating at less than 20% in closed fuel loop during those trips, which combined with the inefficiency of an automatic without the torque converter locked (read: under any acceleration) is going to absolutely kill gas mileage when it's cold out.

I'd guess that you'll see the fuel economy go up with the temperatures. I'd invest in an engine block heater next winter ($30) as it can pay for itself in fuel savings & it's sooooo much better for the motor. Something else you can do is run a lower weight oil (0w-xx) in the winter to combat hard starts when it really dips in temp.

[LeggyxPower]

I've noticed that closed fuel loop doesn't happen super quickly on my Forester after it gets up to temp (keep in mind that it's not actually at temp when the needle gets to its spot, it's probably around 160*F and operating temp is more like 180-190). I would say you're likely operating at less than 20% in closed fuel loop during those trips, which combined with the inefficiency of an automatic without the torque converter locked (read: under any acceleration) is going to absolutely kill gas mileage when it's cold out.

I'd guess that you'll see the fuel economy go up with the temperatures. I'd invest in an engine block heater next winter ($30) as it can pay for itself in fuel savings & it's sooooo much better for the motor. Something else you can do is run a lower weight oil (0w-xx) in the winter to combat hard starts when it really dips in temp.

Here is the kicker i do have a block heater and used it daily, and my car is also garage kept. I had my block heater on a timer to come on about 3 hours before i leave in the morning. i don't use it anymore because the temps around here are now around 0 degrees(32F) but for the whole much of January and february i used it daily as temperatures sat around -25 degrees (-10F)

i think i will go ahead a replace the o2 should do something it has 100k miles on it

[LeggyxPower]

UPDATE:
Past couple week my mpg have been 16 with once hitting 17.02. I bought a Denso oxygen sensor,I'm going to install it tonight and update everyone.

[LeggyxPower]

Well I changed my O2 and reset the ecu.. Half of my tank was strictly highway and the other was city, my total tank was 21mpg [emoji53] I know people say sometimes your mpg goes to crap after a reset for the first little while


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[Wiscon_Mark]

It does - you should wait at least 500 miles before you really take any readings - drive the way you would normally drive so the ECU can set itself up correctly.

[LeggyxPower]

thats what i thought, thanks for confirming, so far i have already driven around 260 miles. I will take constant reading of my tanks of gas to see if there is any differences

[LeggyxPower]

So latest update I did about 30% highway and 70% city and I managed to get 21mpg.... It still drops to 32 F here in the morning....so I would like to think the new oxygen sensor did something, regardless preventative maintenance


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[Wiscon_Mark]

That definitely sounds better.

I've been getting 22-24 in town in my Forester (EJ251) but that's a manual and I have fairly easy in town miles. Sounds like you're pretty on target.