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Old 11-13-2008, 04:49 AM   #1
banana_pony95
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Member#: 171701
Join Date: Feb 2008
Chapter/Region: SCIC
Location: Rancho Cucamonga
Vehicle:
1995 impreza
blue/green

Default IAC Issues

I have a 1995 1.8L subaru Impreza and it seems to have an IAC that is shot. I was wondering if anyone knows exactly how this component works and what a bad one can do to your car (I.E. it's effect on MPG, responsiveness, slugishness, ETC.) This problem is driving me crazy so a responce would be greatly appreciated.

Thanks,
Paul
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Old 11-13-2008, 10:29 AM   #2
Haelan
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IACV (Idle Air Control Valve) is simply a small motorized valve that allows some air to bypass the throttle plate when closed. It continuously adjusts in order to idle at the correct RPM.

If the IACV is your problem you'll probably only notice idling problems and when the throttle plate opens everything should feel normal.
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Old 11-14-2008, 06:00 PM   #3
banana_pony95
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Default Well i"m pretty sure this is affecting my mpg

Yeah, my car's idle is way out of whack. it is never consistant and it is usually too high, but if i adjust it any lower my car will stall out at times. I also notice that when my car has been idling for awhile (i.e. at a signal) the throttle isn't "right there" when i go to accelerate. It is like the idle wasn't keeping enough gas and air in the system while i was waiting. This is such an annoying problem and i need to fix it but the part is either non-existant or $300.00 if i can find one. Do you know of anyone with this part or a cheap source to purchase this part from?
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Old 11-14-2008, 06:10 PM   #4
Haelan
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You might want to look for vacuum leaks before you spend money on parts. You can clean the IACV and that usually helps. You'll need a new IACV gasket in-hand before you take the top plate off.

Search for 'cleaning IACV' for pics and a step by step procedure.

Edit: Are you throwing any CEL codes?
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Old 11-15-2008, 04:55 AM   #5
banana_pony95
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Default Codes?

Well i had a $160 diagnostic done from an honest and professional mechanic and he said that among other things the iacv and map sensor should be replaced. I was just trying to get a second opion and find out how these components worked before i go out and spend alot of money.
I think that if i can i will try and clean the sensors before replacing them. So you sais search for 'cleaning IACV' but where? Usually when i search for such things on google, i never have any luck finding vehicles that are anywhere close to my car. It also doesn't help that i'm not really all that familiar with cars. I've helped work on my car a few times, but only really "know" know how to swap out easy sensors check and replace fliuds and such.
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Old 11-15-2008, 02:13 PM   #6
Haelan
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MAP sensors very very rarely go bad. It is simply a pressure sensor. How in the hell did he manage to diagnose that one without logging the ECU? Did he then compare to a vacuum gauge or boost gauge? If the MAP sensor took a dump you'd have a CEL.

The IACV can get dirty and need to be cleaned. If the electrical components are truly bad you would have a CEL. If the IACV cannot regulate idle at all or the valve positioning gets stuck--again you'd have a CEL.

You need to re-think who you let rip your car apart.
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Old 11-24-2008, 11:28 AM   #7
qstarin
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Old 11-24-2008, 02:23 PM   #8
banana_pony95
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blue/green

Default Thanks

Thank you for that link to the IACV pictures
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Old 11-24-2008, 07:48 PM   #9
Mulder
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Default

Everyone please note that the OP here has a '95 1.8 Impreza, and NOT an '02-05 WRX. Pretty much all of the IAC information posted here references the WRX and therefore will not be applicable in this case.
More accurate responses can probably be had by posting in the Naturally Aspirated forum.
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