Idle Air Control Valve - How often does it actually go bad ? - Subaru Outback - Subaru Outback Forums

SubaruOutback.org is the premier Subaru Outback Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Rate Thread
Old 11-16-2012, 03:23 PM   #1 (permalink)
Registered User
 
Join Date: Jun 2005
Location: Waterbury, VT
Car: 2006 and 2000 Outback Wagons
Posts: 43
Feedback Score: 0 reviews
Default Idle Air Control Valve - How often does it actually go bad ?

I have a 2000 OBW, EJ251 engine, Auto Trans that is experiencing what appears to be the fairly common "rough idle when in gear" problem. The engine never stalls and otherwise runs great. I feel fairly certain that the idle air control valve is causing the problem. I have removed it and cleaned it very well with throttle body cleaner. It almost looked new when I was done. I also cleaned the air passages in the vicinity of where the valve mounts to the throttle body. Everything seems very clean, but the rough idle problem persists.

All other components that I think might be related to rough idle should be in good shape (new plugs, new plug wires, new air filter, new PCV valve, solid electricals/grounds).

My next guess is to replace the valve, but a new one is $300.00 (yikes). I can't really justify spending that much on the problem or a car with 200K miles. I have checked with several local junkyards and no one has a used valve.

So my question to those with much more parts experience (grossgary ?) is, how often do these idle air control valves actually go bad ?
cagranitz is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 11-29-2012, 01:37 PM   #2 (permalink)
I :heart: SUBARU
 
porcupine73's Avatar
 
Join Date: Aug 2006
Location: Buffalo, NY USA
Car: '00OBW, '96&'94 Legacy
Posts: 4,746
Feedback Score: 0 reviews
Default

I have heard a couple cases of them going faulty but not too many. What makes you think the IACV is to blame? Is your engine RPM below the specs when idling in park/neutral and in gear?

The most common complaint of the 'rough idle in gear' problem is having installed a parts store axle on the front.
porcupine73 is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 01:50 PM   #3 (permalink)
Registered User
 
1 Lucky Texan's Avatar
 
Join Date: Jan 2004
Location: behind the Krell Metal door
Car: 03 H6 OBW & 06 WRX Sportwagon
Posts: 7,490
Feedback Score: 0 reviews
Default

^^^ what he said
__________________
Time Flies Like an Arrow,
Fruit Flies Like a Banana!
1 Lucky Texan is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 01:53 PM   #4 (permalink)
Registered User
 
Join Date: Nov 2012
Location: Tomahawk, Wi.
Car: 1999 Subaru Legacy Outback..my son owns it...im in need of vehicle, but cant afford one, i have an old doge caravan not going to last long with all my Dr.'s appt's
Posts: 1
Feedback Score: 0 reviews
Default

My son has same problem with his 1999 outback legacy, i am currently trying to find the reason for this, i suspect the vaccume pressure sensor on the left wheel well, let me know if you figure it out please...THANK YOU...Bernie
Berniepot is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 01:58 PM   #5 (permalink)
Registered User
 
Join Date: Jun 2005
Location: Waterbury, VT
Car: 2006 and 2000 Outback Wagons
Posts: 43
Feedback Score: 0 reviews
Default

The idle appears to be within specs when in gear or park/neutral. It never seems to want to stall, it just gets really rough sometimes with a fair amount of vibration. It comes and goes. Sometimes I can come to a stop and the idle will be smooth, but most of the time, about 3-5 seconds after coming to a complete stop, it will start with the vibration/rough idle.

I removed the IACV a third time and cleaned it really well, but it did not improve the symptoms. I doubted that these actually fail very often since I have rarely heard anyone replace it. A good cleaning seems to be enough.

I guess I am just really skeptical that aftermarket axles would cause this type of vibration/rough idle. But, I am starting to think that may be the issue. I had the drivers side axle replaced back in Sept due to a torn boot. I am fairly certain the prior axle was not a genuine Subaru and I never had a problem with it. I think I may have started to notice the idle problem after that. I figured it was just the car getting old. But after that new axle I noticed a knocking noise when turning and accelerating such as when pullling into traffic from an intersection. I called the shop and complained and they installed another axle. The knocking seemed to be better, but still seemed to be present, but less so. Then a few weeks later, I decided to have the drivers side axle replaced as well before winter set in. The rough idle has remained and maybe even got worse after that. I let it go up to now since it really didn't seem to be hurting anything, it's more of an annoyance.

But now, the knocking noise when accelerating while turning seems to be getting worse. Something is not right. I am taking it into the repair shop tomorrow morning to go for a test drive with the tech.
cagranitz is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 02:02 PM   #6 (permalink)
Registered User
 
1 Lucky Texan's Avatar
 
Join Date: Jan 2004
Location: behind the Krell Metal door
Car: 03 H6 OBW & 06 WRX Sportwagon
Posts: 7,490
Feedback Score: 0 reviews
Default

put it in neutral next time and see if the problem changes/goes away.
__________________
Time Flies Like an Arrow,
Fruit Flies Like a Banana!
1 Lucky Texan is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 02:05 PM   #7 (permalink)
Registered User
 
Join Date: Jun 2005
Location: Waterbury, VT
Car: 2006 and 2000 Outback Wagons
Posts: 43
Feedback Score: 0 reviews
Default

Yes, the idle does seem to smooth out if I put it in Neutral or Park. Strangely, it doesn't really seem to be rough when in reverse.
cagranitz is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 04:43 PM   #8 (permalink)
I :heart: SUBARU
 
porcupine73's Avatar
 
Join Date: Aug 2006
Location: Buffalo, NY USA
Car: '00OBW, '96&'94 Legacy
Posts: 4,746
Feedback Score: 0 reviews
Default

Well let's just say you are not the first person to have this vibration stopped in drive with an aftermarket axle. Just because the prior aftermarket axle didn't do it does not mean the current one doesn't. There are a lot of reports of this exact issue involving aftermarket axles, mainly the cheap parts store rebuilts.
porcupine73 is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 05:16 PM   #9 (permalink)
Registered User
 
Join Date: Jun 2005
Location: Waterbury, VT
Car: 2006 and 2000 Outback Wagons
Posts: 43
Feedback Score: 0 reviews
Default

Yes, that's the impression I got from searching for this problem in the newsgroups. I didn't want to believe the axles were the possible problem, so I was focusing in the IACV.

I will report back after I take the car to the repair shop tomorrow.
cagranitz is offline   Reply With Quote Quick reply to this message
Old 11-29-2012, 10:58 PM   #10 (permalink)
Moderator
 
cardoc's Avatar
 
Join Date: Aug 2012
Location: Austin, Texas
Car: 2001 VDC/SC One of a Kind
Posts: 10,420
Feedback Score: 2 reviews
Default

Rough idle can be caused by poor fuel, dirty fuel filter, ignition plugs, engine or transmission mount issue, loose cv axle joints (which could also cause vibration while driving), torque converter, carbon on the valves, carbon build up in the intake, a dirty air filter, clogged PCV valve or vacuum leak.

The idle will smooth out in P or N due to the release of torque on the drivetrain and lower load on the engine. So pick a place to start and go from there. I would start on what you know is probably due for maintenance or can be seen as a possible cause, i.e. dirty filter.
cardoc is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply


Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Subaru Outback - Subaru Outback Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 04:30 AM.



Powered by vBulletin®
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.3.2
Copyright 2009-2010 SubaruOutback.org. All Rights Reserved.