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Old 01-10-2020, 03:37 PM   #1
zedjr10
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Default 21 mpg combined about. Normal?

I get like 21 mpg combined. Shouldn't it be around 25 or so. I know subaru fudged its number but only 21.

My idle fluctuates sometimes from 700 to 950 or so. It isn't a vacuum leak as it is irregular and unpredictable almost. I assumed at first it was for needed electrical load but ac compressor isn't even cutting on. Is this normal?

What things on this car collect carbon deposits that i can clean. Of course the throttle body. What else? On my old honda i clean a few things every 50 to 100k miles like the EGR valve, IACV, and throttle body.

Do these sensors like egr measure flow? Or just if it works or not. What other sensors to clean besides Mass Airflow?
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Old 01-10-2020, 05:43 PM   #2
IHaveAHorse
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Have you ever replaced your fuel filter? Spark plugs? Use a large bottle of techron in half a tank of gas maybe, I swear it helps when my MPG seems to be dipping excessively every year or two. Also could try the seafoam throttle body spray.
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Old 01-10-2020, 06:50 PM   #3
zedjr10
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Originally Posted by IHaveAHorse View Post
Have you ever replaced your fuel filter? Spark plugs? Use a large bottle of techron in half a tank of gas maybe, I swear it helps when my MPG seems to be dipping excessively every year or two. Also could try the seafoam throttle body spray.
Spark plugs, air filter, seafoamed throttle body and fuel injector cleaner so far. Also cleaned Mass Air flow. Where is this cars Idle Air Control Valve? Probably will solve my idle jump when ac cuts on. AM assuming it has one or something similar attached to intake manifold.
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Old 01-10-2020, 09:21 PM   #4
DieselDorf
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Seems really low.

Check the parking and all brakes for rubbing, itís a really common issue they have, after a long drive sometimes you can just feel heat when putting your hand in he wheel spokes
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Old 01-10-2020, 09:36 PM   #5
IHaveAHorse
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The RPM is going to change when the AC compressor comes on, it takes a lot of power to run that inefficient hunk of high friction metal. Pretty much all cars do that.
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Old 01-10-2020, 11:47 PM   #6
zedjr10
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Originally Posted by IHaveAHorse View Post
The RPM is going to change when the AC compressor comes on, it takes a lot of power to run that inefficient hunk of high friction metal. Pretty much all cars do that.
No most cars don't as they have some sort of idle air control to even things out as an alternator takes a load from engine. If iacv didn't kick in the rpms would drop. It is just there to keep it stable while cutting off and on and with anything else electrical. Some will jump 50 rpms or so but 250 rpms spikes didn't even happen in older cars with older iacv controls. If this is the one off car that does this by design i doubt it being it 2014 model and not 1975.

Whatever the idle air component is probably has carbon build up in the air passages somewhere. Can anyone point me to where the Idle Air components are? This freakn service manual is confusing as heck. Am new to these boxer engines.


Diesel dorf. YOu mean the brakes rubbing while am driving causing bad gas mileage. It isn't that.

If my car doesn't have an iacv then what mechanism does it use for load adjustments. The throttle plate or some other mechanism for additional air introduction?

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Old 01-10-2020, 11:53 PM   #7
IHaveAHorse
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You're actually just wrong but OK.
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Old 01-11-2020, 12:40 AM   #8
zedjr10
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You're actually just wrong but OK.
Cars don't change that much. My alternator can pull the load it needs at 700 rpms. 1k is not needed and i don't believe 700 to 950+ rpm shift is needed to run my fan. Not even on my old accord with an older alternator is that needed.

Slight rpms changes is expected when compressor kicks in but not 300rpms. THat doesn't sound normal. I thought it was cause of a cold engine but let engine warmp up for half hour today and it did same thing.

Does this car even have any thing resembling an idle air controller or is changed simply thru the throttle plate? Even if it is. I doubt 300rpms is normal. Is it?
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Old 01-11-2020, 01:44 AM   #9
IHaveAHorse
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Are you sure it's 300rpm? Have you used an OBD monitoring software? Mine does and always has gone up 100-200 at least.
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Old 01-11-2020, 01:34 PM   #10
zedjr10
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Originally Posted by IHaveAHorse View Post
Are you sure it's 300rpm? Have you used an OBD monitoring software? Mine does and always has gone up 100-200 at least.
So totally normal this is? All because fan or compressor cuts on? It is between 250 to 300rpm jumps at times. Will check this again this weekend.

I don't have any OBD monitoring software. Will get an obd2 scanner soon. My honda is obd1(old it is).

Is there any idle air control component. My service manual talks about it but i can't find its location anywhere in service manual. So is there any air passages that need to be cleaned anywhere?

I am new to subaru and the boxer engine. SO far i love it but am totally unfamiliar with it. Alot of weird things on a boxer engine i don't recognize. Sorry if i pretend to know something i may not know. I make assumptions based on what i know from older hondas. Never had a car that jumps idle like this one so much.
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Old 01-11-2020, 02:05 PM   #11
awfulwaffle
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Def low for an NA. This is what my turbo cars get.
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Old 01-11-2020, 04:17 PM   #12
DieselDorf
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I realized why my mpg went fown about 3 mpg I just changed my air filter and t was really cruddy.

I did a lot of miles so probably should have changed it a while ago.
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Old 01-12-2020, 06:14 PM   #13
Cifcik_
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Originally Posted by DieselDorf View Post
Seems really low.

Check the parking and all brakes for rubbing, itís a really common issue they have, after a long drive sometimes you can just feel heat when putting your hand in he wheel spokes






Hey speaking of rubbing, ever since I did my brake change thereís been a tiny buzzing sound when I step on the brakes coming from the rear brakes :0 anyone???? Sounds like a baby tattoo machine lol
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Old 01-12-2020, 06:42 PM   #14
IHaveAHorse
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Did you lubricate that notch on the sides where the pad backing plate sits in the grooves on the caliper? Could be vibrating or something if it's nice and rusty with high friction. I have some kind of rubbing at like 30-45mph that's super faint, I can hear it with my windows down decently well when there's no other traffic around. I still haven't figured out what it is but I'll look next time I rotate my tires.
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