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RIP 2000 2.5RS, 1999 RS
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519 Posts
Discussion Starter · #1 ·
Recently I've been getting 12.9 MPG in my 2.5rs, it's completely stock exept for the K&N Panel Filter, I get a CEL for my knock sensor, it comes and goes, could this be the problem? or maybe my o2 sensors are going?
 

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12,196 Posts
Any CEL will dramatically reduce your MPG's. Clear it and get it fixed and you should be fine. Other than that, check the normal stuff... tire pressure, plugs, wires, air filter, fuel filter, pcv etc etc.
 

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needs more cowbell
95L, 07 2.5i, R6
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9,316 Posts
Maybe some of the oil from the k&n is fouling a sensor in the intake tract? Otherwise, that is some seriously poor mileage. Is it an auto as well?
 

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1993 Impreza wagon AWD
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450 Posts
I have a 1.8 that's sometimes been under 15. Don't worry too much, just get the problems fixed.
 

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needs more cowbell
95L, 07 2.5i, R6
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9,316 Posts
Are you sure you don't have a partially clogged catalytic converter? wow
 

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Premium Member
96 GF4 " Bruiser"
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3,542 Posts
yes it would. would make alot of things go bad. can burn up your cat (the converter kind) and really toast your plugs
 

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Registered
RIP 2000 2.5RS, 1999 RS
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519 Posts
Discussion Starter · #13 ·
I'm not sure what knocking or pinging sounds like so I don't really know
 

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4 please, to go.
Ver 7 STi GC, elderly L
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3,623 Posts
That's exactly the mileage I was getting when A/F sensor went bad. But I had a CEL for it.
 

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RIP 2000 2.5RS, 1999 RS
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519 Posts
Discussion Starter · #18 ·
I'm going to replace my knock sensor today and see if I get any improvement
 

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Registered
RIP 2000 2.5RS, 1999 RS
Joined
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519 Posts
Discussion Starter · #19 ·
Just replaced the sensor, and drove around for about 23 miles and the gauge barely moved, I'll keep driving it a bit to see if my problem has been solved, I'll keep you guys posted.
 
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