Gas mileage.. I feel too low.

[seabass07]

If I let the car idle for 5 minutes, I can watch the mpg go down. That will definitely throw off the numbers. You may want to get a block heater.

[AZZMAN]

I'm just glad your not too high.

[Foo]

The car is reading 13.5mpg for my city driving.

 

How consistent is the idle when the engine's warmed up? Any faltering/hesitation? Are the exhaust tips blackened up?

 

Highway/distance drives should give you a better indication as these cars don't seem to be the most efficient for stop-start and low-speed stuff. Definitely not cheap for commuting.

[thefultonhow]

Stock, I was getting 17-23. Stage 1, 13-17. We'll see what Stage 3 gives me...

[vr4Legacy]

I say don't use the auto start for a few days and reset your trip. See what that yields you. It's amazing how 5 minutes turns into 10 when you are getting ready to head out the door... my mom averages 16 on her Forester during winter because she uses her heater... and she DOES drive like a granny

[mwm5094]

This happened to me. I was getting 11.5 tops in town and 15 tops highway. It was my O2 sensor in the headers. It was bad and therefore causing my car to dump as much fuel as possible in the engine because it did not know how much was needed to properly run so it dumps a ton of fuel just in case if that makes sense. Hope this helps. Good Luck

[blongo804]

Thank you so much everyone for your suggestions! With gas going up and already having to get 91 octane, it gets expensive being 18. I'll have my father check my o2 sensor(s). If one has failed, wouldn't it throw a CEL?

[ehsnils]

Not necessarily - if the signal is within range of a working one it may still be determined as good by the ECU.

 

And if you start to replace parts it's good to have a controlled reference consumption to compare with so you see the difference.

[Garandman]

The car is reading 13.5mpg for my city driving. I have a 5EAT tranny, a 1200 mile new shortblock/turbo and use 91 octane. What am I doing wrong? My brother drives an '03 WRX stg.2 (I think?) and gets better mileage than me. Is it the new block not broken in yet? //

I logged all fuel use and my H6 improved for nearly the first 20,000 miles. It improved a lot in the first few thousand.

 

But short city trip from a cold start, 13.5 would surprise me. My wife does 100% city driving in her minivan and averages 13-15. Put it on the highway and that same van gets 22-25.

[blongo804]

I was getting 13.5mpg from using the manumatic mode. I just did another trip in full automatic and got 12mpg, so that's where I stand right now. I'm refilling today to try again using the manumatic (shifting between 2-3k).

[bmx045]

Cold weather worsens gas mileage...also certain winter fuels that are used up here in NE kill mileage.... I wanna cry, 93oct is $3.20 here! As soon as you go into boost you can kill the cash goodbye. I'm on a stage 1 map in sport #. Regular sport mode is better since you don't find yourself in boost all the time...

[f1anatic]

Hmmm. I get 30-33 mpg on the highway; 18-22 in the city.

[bmx045]

That's GOOD. I sit in traffic all day. Just installed a tranny cooler to reduce the RAPE my transmission endures.

[ehsnils]

That's GOOD. I sit in traffic all day. Just installed a tranny cooler to reduce the RAPE my transmission endures.

 

Do you have a thermostat on it - otherwise the oil may get too cold during winter - increasing fuel consumption.

[bmx045]

thermostat on the tranny cooler? It routes through the radiator and then the cooler and then back to the tranny.

[ehsnils]

OK, then you are good.

 

I thought you mounted a separate cooler.

[Foo]

If any of the things I listed check out, then you may have blocked or partially blocked injectors.

[f1anatic]

Do you have a thermostat on it - otherwise the oil may get too cold during winter - increasing fuel consumption.

 

 

This is the most silly thing I have heard. I even had a fight with another member over this.

 

There is a significant misconception about the effect of a colder thermostat. Well I have one. And it is -10 C outside right now. As cold as cold gets in Chicago. My coolant temperature, driving on the highway was 80-81 C 20 minutes ago. I installed the Grimmspeed 160F thermostat in October, along with new water pump and coolant. So everything is fresh.

 

Summer temperatures on a regular thermostat are at 88-90 degrees Celsius . Normal winter temperatures on a regular thermostat are about 83-85 C. At 93 C your HVAC will stop blowing air conditioning during summer.

 

I have a freaking CarPC with tactrix connected to OBD-2 and I have been staring at coolant temperature in real time for more than 3.5 years. That's how I know.

 

And I still get 30 mpg with a cold thermostat in arctic temperatures on the highway. Its effect is insignificant on the temperatures in terms of getting your oil thicker in winter. In the summer it might mean the difference between your engine reaching 93 when idling in a long traffic jam and getting nice air con.

 

A colder thermostat only means about 3 deg. C colder temperature.

[ehsnils]

This is the most silly thing I have heard. I even had a fight with another member over this.

 

There is a significant misconception about the effect of a colder thermostat.

 

Not about a colder thermostat - I was from the context thinking a separate oil cooler without a thermostat at all - which in turn would result in the fact that the oil never would get up to working temperature.

 

But that was a misunderstanding of concept.

 

A colder thermostat - no - that would have a very small impact - other factors would be hiding the difference.

 

So a complete misunderstanding...

[bmx045]

Not about a colder thermostat - I was from the context thinking a separate oil cooler without a thermostat at all - which in turn would result in the fact that the oil never would get up to working temperature.

 

But that was a misunderstanding of concept.

 

A colder thermostat - no - that would have a very small impact - other factors would be hiding the difference.

 

So a complete misunderstanding...

 

 

I was talking about a transmission fluid cooler, not an oil cooler.

[seabass07]

They don't usually have thermostats though. It is just a pressure bypass so the fluid bypasses the cooler when the cooler is full of gelled fluid.

[blongo804]

Well, a month later and here I still am..

 

http://i52.tinypic.com/fy37et.jpg

 

O2 sensors checked out normal for what we believe. Unless this car's O2 sensors read differently than normal ones, the numbers appeared normal as per what my father and his other fellow mechanic friend said. They've both been in the business for 30 years now but my dad has admitted he's not 100% sure as to whether or not Subaru O2's read different because he doesn't like working on them lol. One was swinging around .6-.8 millivolts and one was around 2.7-2.9 volts the whole time. Does this sound right?

 

Everything I suggest we do, he denies though. He's a very stubborn guy. I tell him could it be clogged/dirty injectors? No, it would be doing this. Could it be etc., no..

 

The WORST part is, local Subby dealership says my mileage is normal and Subaru's get bad mileage in the winter... in other words, please help me LGT.com!

[Merc6]

This happened to me. I was getting 11.5 tops in town and 15 tops highway. It was my O2 sensor in the headers. It was bad and therefore causing my car to dump as much fuel as possible in the engine because it did not know how much was needed to properly run so it dumps a ton of fuel just in case if that makes sense. Hope this helps. Good Luck

Yep this and the egt sensor in the up screwed me on mpg. I felt like I was driving an excursion from the needle moving soo much.

 

Well, a month later and here I still am..

 

http://i52.tinypic.com/fy37et.jpg

 

O2 sensors checked out normal for what we believe. Unless this car's O2 sensors read differently than normal ones, the numbers appeared normal as per what my father and his other fellow mechanic friend said. They've both been in the business for 30 years now but my dad has admitted he's not 100% sure as to whether or not Subaru O2's read different because he doesn't like working on them lol. One was swinging around .6-.8 millivolts and one was around 2.7-2.9 volts the whole time. Does this sound right?

 

Everything I suggest we do, he denies though. He's a very stubborn guy. I tell him could it be clogged/dirty injectors? No, it would be doing this. Could it be etc., no..

 

The WORST part is, local Subby dealership says my mileage is normal and Subaru's get bad mileage in the winter... in other words, please help me LGT.com!

How hilly is it there where you are? Most of my turnpike drives from here to jerz are almost hills.

 

How many miles are you driving on that trip meter?

 

Are you also using pump from pump #4(or whatever pump you normally use) drive X amount of miles and them pump again from that same pump method noting miles vs gals refiled? Not sure if it's a 05 thing or not with trip mpg but it never tells me anything useful. I could be 20 miles from empty and the needle would be 1/8 and it still say 20 on empty. I haven't used 91 even tho the pa turnpike has it.

 

Shifting manual are you holding the lower gears or mimicking the trans in d shifting to 5th as fast as up arrow pops up allowing you to? In manual mode I was finding myself downshifting a lot anticipating a pass on slower cars and never passing them right away. I end up holding 3rd or 4th too long well beyond the normal time leaving me @3800-4200 rpms. another thing I do in traffic is leave it in 2nd and stop go stop go stop go if they aren't going to drive fast or far between. 2nd gear from a stop will hold 2nd all the way through stop and go.

[blongo804]

It's definitely pretty hilly here unfortunately. I have to drive up about 5-6 blocks of hills every day just to get home from school. I don't even go fast up them either, just take it easy is all.

 

On that trip, it might've been about 180 miles because that's what I get to a full tank. The picture was taken about 2 weeks ago and I reset every time I fill (after realizing my mileage is too low is why I reset a lot) but with no better mileage any time. I've never actually done a miles v gallons filled test yet because I've been relying on the computer in the car since I hear they're somewhat accurate. Actually at the moment I'm keeping a long trip going and just going to keep filling.

 

I shift manual all the time. Each shift is between 2-3K and at most, 3.5K. I'm never boosting or having fun because once I do, the gas goes even quicker and I average 4mpg. I seriously never beat on the car and drive it slower than my old '95 Legacy LS. I hear it all day from my sister to drive faster home from school. Do I listen? No .

 

As for downshifting, occasionally I'll get into 2nd before I go up a hill. It just depends on the steepness.

 

Also to add, even in October with normal chilly weather, I was average 13.x. Nothing CLOSE to what anyone on this site gets.

[Merc6]

I usually go 3rd gear and watch my rpms. I have quite a few hills here and 3rd gear was decent. In D you have to apply more gas at the base of the hill to get it to wanna downshift or it will fight you most the way up. On a stock turbo w/ down pipe I could hear the wga flutter for like 8/10 seconds in 5th before it would kick down. After 40 MPH these trannys like to shift to 5th and fight you to let go. Winter gas mix is not gonna be the best either.