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05-01-2021, 11:04 PM | #1 |
Scooby Newbie
Member#: 522523
Join Date: Feb 2021
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Bad fuel economy.
So I bought a 2009 Impreza Outback Sport that gets worse fuel mileage than my 2001 Forester. The car itself is in excellent shape, just abysmal chugging. The car has 104k, spark plugs and wires were changed at 96K, air filter looks newish, Tires are almost brand spanking new, What else could be doing this mechanically? PCV valve clogged? Fuel filter? Timing belt will be done in a month of course.
Does the TPMS light trigger a fuel-air worse fuel-air ratio?
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05-01-2021, 11:22 PM | #2 |
Scooby Newbie
Member#: 521349
Join Date: Dec 2020
Chapter/Region:
South East
Vehicle:2005 STI Aspen White |
Not too well versed on NA Subaru engines nor that year or model but Generally under inflated tires do consume a little more fuel.
How bad of a difference is your fuel consumption? |
05-02-2021, 02:02 PM | #3 |
Scooby Guru
Member#: 141373
Join Date: Feb 2007
Chapter/Region:
E. Canada
Location: Quebec, QC
Vehicle:2022 Crosstrek Sport 6MT |
There is no TMPS-related "trigger". Also, gas mileage is a resultant of many, many factors - it's really hard to say if anything is wrong. Headwind, ambient temperature, tyre pressure, elevation, inclination, trip duration, speed profile (the actual curve of speed vs.time), acceleration, deceleration (amount of stops, red lights, braking vs. coasting), cargo load, MT vs AT, ethanol percentage in the fuel... all of those yield the ultimate "mpg" value.
The engine is nearly the same: the Forester had the EJ251, the OBS has the EJ253 which is a little bit more economical. The OBS is also more aerodynamic as opposed to the boxy Forester. If you want to compare yourself to others, have a look at Fuelly, and look at 2008-2001 imprezas (2.5i, premium, OBS...). Averages hover around 24-25mpg, but uou also see the entire statistical distribution. https://www.fuelly.com/car/subaru/im...ubmodel_id=115 Mind you, with a 2009 that you have just bought, you do need to check a few things (if you didn't already). Maintenance records, spark plugs, tire pressure, brakes, air filter, vacuum leaks, etc. Last edited by Bluefoton; 05-02-2021 at 02:25 PM. |
05-02-2021, 02:38 PM | #4 |
Scooby Newbie
Member#: 245853
Join Date: May 2010
Location: Central, PA
Vehicle:2010 STI SE Aspen White |
What mpg are you currently getting? I get about 25 mpg at 70 mph highway driving with my 99 Legacy SUS 2.5 Liter.
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05-03-2021, 01:33 PM | #5 |
Scooby Specialist
Member#: 80465
Join Date: Jan 2005
Chapter/Region:
RMIC
Location: Denver
Vehicle:2001 2.5RS Black Diamond Pearl |
Could be a non-engine factor, such as a dragging brake.
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05-06-2021, 03:17 PM | #6 |
Scooby Newbie
Member#: 522523
Join Date: Feb 2021
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Good point... I'll check that out too.
Thanks for all the replies guys. Sorry, haven't had a chance to check back here in a few days. I just had all 4 shocks replaced with KYB, but the bad fuel economy persists. Here's what I know: I had the tires inflated to spec with nitrogen at the dealer a few weeks ago, so even though the TPMS light is on, I'm pretty sure they're not underinflated. It's nothing obvious while driving, anyway. Spark plugs that were replaced @96K by Christian Bros. automotive for the prev. owner were NGK 5464 Iridiums. The Owner manual calls for NGK 5463 Laser Platinums. Wrong heat range plug maybe? Where is the PCV valve located in this car? is it the same on top as an EJ-25 motor from 2001? I want to check that first. Thanks again. |
05-07-2021, 10:34 AM | #7 |
Scooby Newbie
Member#: 522523
Join Date: Feb 2021
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Anyone here? Where did you guys go?
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05-09-2021, 07:58 PM | #8 |
Scooby Newbie
Member#: 520833
Join Date: Dec 2020
Chapter/Region:
Tri-State
Location: South East PA
Vehicle:2010 Impreza 2.5i Pr |
top passenger below throttle body and coil pack
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05-11-2021, 04:11 PM | #9 |
Scooby Specialist
Member#: 459287
Join Date: Dec 2016
Chapter/Region:
VIC
Location: Vancouver BC Canada
Vehicle:1998 JDM Impreza STi V4 GF8 White |
Check if one rotor gets hotter than the others
I was suspicious of dragging brakes... so after a short drive, I touched each rotor through the wheel with the knuckle of one of my fingers. I quickly found the culprit. Turns out one rear caliper seal was torn, and this had allowed water to enter and corrode the piston (which had become semi-stuck in the bore).
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05-12-2021, 03:40 PM | #10 |
Scooby Newbie
Member#: 524256
Join Date: May 2021
Chapter/Region:
BAIC
Location: CA
Vehicle:2006 Legacy 2.5i Silver |
Could be you need a new maf or vacuum leak. No CEL present?
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05-12-2021, 10:00 PM | #11 |
Scooby Newbie
Member#: 522523
Join Date: Feb 2021
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05-12-2021, 10:01 PM | #12 |
Scooby Newbie
Member#: 522523
Join Date: Feb 2021
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