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Low MPG, what to check for?


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Hey guys, I am learning my new [old] car and noticed i've been getting relatively poor mileage. Try 14 mpg, under slow driving <2500 RPM avg.

 

I've noticed that the muffler tips are dark, could i be running rich or is that normal among our car?

 

what are some things to check for to ensure better mileage?

I know about spark plug and air filter, but what else?

I want to visit the garage and have them check everythign out.

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ive been getting 17.5 city ... 24 highway about.. im stage 2 cobb... ive seen a few threads and talked to some of my buddys thats the norm for a stage 2 tune least so iver heard ... ive changed my filter, fuel filter, oil from 5/30 conv to 5/40 rotella..

havn't done plugs yet. going to tackle that after winter along with my pcv valve and hoses....

 

you tuned ? what kind of tune?.... that does sound low. and how many miles on the car ....

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I'm 100% stock and only getting 20MPG highway mileage, average 45-50mph.

I have good oil, plugs etc. Not sure what's wrong but I'm only getting 250+/- miles out of a tank...

Alignment, oil, plugs, filters etc is all I can think of checking and getting replaced

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My wagon read 27mpg on the way back from VT yesterday, doing 68-72mph on CC.

 

You guy's need to talk to Tuner. Here's who I use.

 

http://legacygt.com/forums/forumdisplay.php/tuning-alliance-121.html

 

Contact Mike. Tell him I sent you.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.

 

Engine Build - Click Here

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i ran from philly to atco n.j... last week.. i got avrg of 24.7 mpg and thats still not a steady run .. took rt 73, so its till has a good bit of lights ... alot my my traveling is stop and go .. i really dont bother looking at my mpg alot.. i enjoy driving the car to much since i went stage 2 lol ..

 

ive jumped on it with my buddy behind me ... not a drop of smoke.. so not running rich .. im only on a cobb tune so ...

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I drove it in manual today, and I noticed I loves 3rd and 4th gears for saving gas. Right at ther 2K RPM mark.

 

It's now 7.5 KM/L or 18MPG. BUt that's driving like grandma. I know you guys get better even squeezing it a little :)

 

Gas in my country is 10% blend of ethanol.

 

Lucky me, I get an STI rally mechanic to look on it tmr :D

 

Next month I'm getting a stage 1 like tune :D and the guy will also adjust the ECU wor work with our lower octane gas. The car is JDM so she was programmed for 98RON, and our gas is ~94 max (90 RON+MON)/2

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I've got a non-GT and I routinely get 25mpg around town by the computer (which is about 2 mpg optimisitic when I checked it). I can get up to an indicated 30 if I'm careful and the best I've done on the highway is 35.

 

The ethanol will cut your gas mileage, but if it's dropped and the fuel HASN'T changed, then it's something else (unless the ethanol is screwing something up).

 

Steve

 

2005 Legacy L wagon

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the computers in these cars, so ive been told, are smart enough to sense the type of fuel used based on knock sensor readings. the lower octane the fuel, the more violent the explosion, and the higher reading the knock sensor recognizes. the ecu will retard timing or electronically limit boost. less air means a rich fuel mixture. if youre running a jdm car, it may be worth looking into swapping an american ecu (not sure if thats possible) thats tuned for lower octane readings. in a pinch, ive used 89 fuel and it ran just fine, getting around 24mpg. good luck!
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