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Stage 2 help! Losing MPG?


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As with many others here, I, too, have seen, surprisingly, a gas-mileage increase since I've gone "Stage II."

 

Many will say that this is due to tighter tune of the air-fuel curve, as well as freeing-up the exhaust side of the equation, and I would tend to agree with both.

 

However, it should also be noted that these brothers - and myself - also constantly will remind newcomers to this level of tune that your MPG will be *highly* dependent on your driving habits. Hammer on the car at-all (i.e. as soon as that boost needle goes positive), and you'll see your gas-mileage drop like no tomorrow.

 

On my last long road-trip, which I took this weekend, for a drive of nearly 700 total miles, I averaged nearly 27 MPG, cruising most-times at around 75 MPH. And this, mind you, was with about 100 miles of city-driving mixed-in to the equation - plus really dropping the hammer at every on-ramp and toll-booth. :lol:

<-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges

'16 Outback, '16 WRX, 7th Subaru Family

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Yea - stage 1 = lower fuel economy all around.

Stage 2 = even lower yet if you drive with a lead foot, but cruising on the interstate (nonstop) I get about 1 mpg higher fuel economy than before upgrading anything.

[CENTER][URL="http://legacygt.com/forums/showthread.php?t=18504"]Subaru Plug & Play Aux-in Mod[/URL][/CENTER] [CENTER][URL="http://www.jazzyengineering.com"]www.jazzyengineering.com[/URL][/CENTER]
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I am going to do the GFXDave experiment. I am going to stay entirely under 3k rpms. I'll be Trying to shift around 2500 rpms and keep the revs as low as possible while driving. I'm hoping this will net me 18-19 mpg. I only got 14.1 mpg on my last tank (actual calculation) At least premium is only 2.38 around here :/
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I'm with VTGT and the gas mileage but I attribute it to my rather moody foot. I love to boost and I know it so I just deal with the crappy mileage. I think the last time I looked at the avg reading it said something like 17.5 or 18.5mpg. I do mostly city driving and i average around 250miles per tank compared to when I used to commute I would get 350 per tank.

 

 

 

Today's daily lesson:

 

It cost to drive anything but it cost even more to drive something fun.

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I am going to do the GFXDave experiment. I am going to stay entirely under 3k rpms. I'll be Trying to shift around 2500 rpms and keep the revs as low as possible while driving. I'm hoping this will net me 18-19 mpg. I only got 14.1 mpg on my last tank (actual calculation) At least premium is only 2.38 around here :/

 

$2.38/gal for premium! :eek: I almost wet myself with joy when I saw a station here where premium was $2.99/gallon. Been paying more than $3/gallon for tha past year.

 

With regards to the low rev experiment, it works. I shifted from 1 to 2 at 2800 rpm, 2 to 3 at 2600, 3 to 4 at 2400 and 4 to 5 at around 2200. All at light throttle. More or less kept up with traffic, and got 24 mpg in the city. Did this for half a tank and got so pissed off that romped on it all the time for the last half tank. Ended up getting 20 mpg overall.

 

Moral of the story for me is that the car is capable of decent to good mileage, but is absolutely no fun to drive when all you are trying to do is bump up the mpg's. I'll pay to play.

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Moral of the story for me is that the car is capable of decent to good mileage, but is absolutely no fun to drive when all you are trying to do is bump up the mpg's. I'll pay to play.

I agree. Enjoy it! Otherwise, go buy a Prius. :p:D:lol:

 

BTW, I'm sure this is posted elsewhere, but Legacy_Otaku is my friend who I invited to the SCS event so that he could ask you guys questions about the car and available mods. I plan on giving him a hard time on the boards. ;)

 

-Mike

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So after 30 miles the computer is reading 15 mpg. I haven't shifted past 3k rpm in any gear. I know the computer isn't terribly accurate but it is still somesort of measurement. I was expecting it to read at least 17.
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Double check your vacuum lines, especially the one underneath the intercooler that goes to the manifold (look for the blue tee). You can have a vacuum leak without triggering the P0171 code. If there is a leak, the ECU will be upping the fuel correction values, which will severely degrade your fuel economy. I had the vacuum line pop off my MAP sensor without triggering a CEL, and my city fuel economy dropped from around 20 to 16-17mpg. Finally figured out the problem with some TARI datalogging.
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Double check your vacuum lines, especially the one underneath the intercooler that goes to the manifold (look for the blue tee). You can have a vacuum leak without triggering the P0171 code. If there is a leak, the ECU will be upping the fuel correction values, which will severely degrade your fuel economy. I had the vacuum line pop off my MAP sensor without triggering a CEL, and my city fuel economy dropped from around 20 to 16-17mpg. Finally figured out the problem with some TARI datalogging.

 

 

I'll check that, thanks. There wouldn't be any damage i there was a vaccum leak would there?

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I was getting numbers like that--and I still average about 260 miles per tank. By the way...I'm STOCK.

 

I don't know if that is normal. A lot of people under the same (or worse) conditions are able to pull a lot more miles out of their gas tanks.

 

I don't drive very aggressively, and I've tried shifting at 2-3K but that doesn't help. I've also used Shell V-Power only for the last 6 months with no real difference. I tried Marathon a few days ago and that seemed to help but not that much. I'm still right around 260-270 miles/tank.

 

Maybe Subaru had a bad batch or something?

 

 

 

+1

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I just thought about something else. Could a bad alignment cause me to get bad gas mileage? I think I may get a realignment and rotate the tires. This is my first time doing it and my car has 6700 miles.
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No, a bad alignment isn't going to drop it by 3mpg city.

 

I would definitely check your vacuum around your intercooler. I knew a guy with stage 2 LGT who blew off his intercooler manifold, as discussed earlier on this thread. He noticed this 20% decrease in mpg and the car wanted to stall when it was in idle at a stop light. Are you experiencing anything like this?

 

Maybe you just got some bad gas.

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A bad alignment, while probably not enough to cause 3-4 mpg drop, can cause reduced mileage. Same can be said for improperly inflated tires (underinflated). WRT the alignment, if your rear tow is out of wack, you'll essentially be scrubbing / pulling the tires. I got my alignment corrected under warranty, stock it looked like this (I'm exaggerating, but the tow was like this):

 

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