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Discussion Starter · #1 ·
I have made some posts on here before about my OB getting bad mileage (16.5-17mpg in city) Recently went through and replaced and tested multiple components. Heres the run down:
-No CELs (Has had an anti-knock CEL in the past, and a misfire, but these haven't come back since new sensor and plugs)
-New Anti-knock sensor
-New coil pack, plugs, and plug wires
-New fuel filter
-New Battery
-Tested O2 sensors, impedance across heater circuit is good, and power is supplied to the circuit
-Tested MAF sensor, good readings
-Tested compression at warm engine temp, all 4 cylinders within ~8 psi of 180psi
-Tested waveform of O2 sensors using a OBD reader, sensors bounce between .05 and .9. Creating a vacuum leak effectively causes a drastic change in voltage

What could be wrong with this engine? I don't want to have to spend money changing the timing belt or replacing fuel injectors if those aren't the likely culprits. Ive heard that grey top injectors are extremely reliable, and these are the ones I have. Is there any sort of pre filter in the tank that could be clogged? Are clogged cats a real thing? The car is registered in Montana, so I would be ok with taking the cats off and spacing the rear O2 sensor out of the stream if needed.
Any ideas are appreciated.
 

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Premium Member
2020 Onyx
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11,176 Posts
Are clogged cats a real thing?
Yes clogged cats are a real thing but you should notice power loss and drivability issues under full throttle.

I didn't read your other posts - is highway fuel economy good?
 

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On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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26,960 Posts
1st off is this

a legacy with a 2.2 ?

or a legacy outback with a 2.5 ?

or a impreza outback sport with a 2.2 ?

auto or manual ?

(your avatar pic seems to have a wise pup standing in a gen1 legacy outback.....the only gen 1s that came with the great 2.2 was the 1996 manual, and the half baked 1995,...see the engine stamp on the short block, and on the build plate on the shock tower in front of the driver).
 

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Discussion Starter · #4 ·
Yes clogged cats are a real thing but you should notice power loss and drivability issues under full throttle.

I didn't read your other posts - is highway fuel economy good?
Highway fuel economy is only about 22-25 mpg. And yes, actually, full throttle feels very weak. The car has a ton of trouble climbing hills.
 

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Discussion Starter · #5 ·
1st off is this

a legacy with a 2.2 ?

or a legacy outback with a 2.5 ?

or a impreza outback sport with a 2.2 ?

auto or manual ?

(your avatar pic seems to have a wise pup standing in a gen1 legacy outback.....the only gen 1s that came with the great 2.2 was the 1996 manual, and the half baked 1995,...see the engine stamp on the short block, and on the build plate on the shock tower in front of the driver).
You’re right! It came with the 2.5 but that blew up so its an ej22 swap.
 

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Premium Member
2020 Onyx
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11,176 Posts
It sounds like a clogged cat is a good candidate.
 

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On the Super Mod Squad
2002 3.0 VDC Wag + 2018 2.5 Leg Ltd
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26,960 Posts

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Premium Member
01 VDC, 05 R Sedan, 06 BAJA EJ257
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15,905 Posts
22-25 on the highway is good. As for up hill driving it could be timing related so I'd at least pull the side covers and check it. Fuel filter??????

If you want to "test" up hill driving, drop the cat pipe and drive it. It'll be loud, but it will give you an indication. Just leave the rear O2 unplugged, it won't bother fueling, just turns the MIL on which you can clear later.

Another thing is to think.about higher octane gas. High octane equates to less detonation, less frequent fuel.adjuatmwnt by the ECM and the engine will run cleaner.
 

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2001 2.5 RS & 2000 OB
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253 Posts
Don't rule out that something might be holding you back. Extra drag from brakes not fully releasing is a possibility, as is a dying wheel bearing. Clean your engine/chassis grounds. Even go so far as to add an extra one.
 

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Premium Member
2020 Onyx
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11,176 Posts
Do torque converters fail to lock up? That could be another source of poor fuel economy though I haven't heard of this being an issue.
 

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1995 Legacy 2.2L | 2005 Outback XT 2.5L
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108 Posts
I drive a 1995 Legacy (2.2L) and I usually get about 18 city, 21 hwy. Honestly the plugged cat thing could be a good guess but tbh I think that's just what they get man.

Also, the higher octane gas thing is real. Currently running mine on 91 this week as a test and it feels a lot more responsive and seems to run smoother. No real difference in acceleration, but the throttle response is better and it seems more eager to go, especially at low RPM.

Oh yeah and I tried to baby it last week and I only got about 19.5 mpg :(. With the rising gas prices, I might just buy a cheap Honda Fit to drive as a commuter lol
 
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