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Old 01-20-2010, 10:06 PM   #1
trbo_blu
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Default 2007 WRX - Idle Air Control Valve?

I just picked up a 2007 WRX last week. The car does have 68K miles on it, but supposedly they are all highway miles. But anyways, at times during idle, it will drop down below 500 RPM and then surge up past 1200 or so RPM. It does it maybe once or twice a day randomly while sitting at a stop.

I did a search on idle issues and came across several posts recommending that the Idle Air Control Valve be taken off and cleaned as dirt and oil buildup can occur inside and cause idle issues. I was going to order a gasket to make sure I could replace it after taking off the valve.

However, I found a post which I can't find it now that someone had said the 07 didn't have a IACV. Its dark outside and I don't have a flashlight here at my apartment to go out and take a look to see if I see it or not. So my question is, was that a legitimate post or does the 07 WRX have a IACV?

If it does not, what other recommendations do you have? It hasn't thrown a code and doesn't do it that often. When does Subaru recommend a plug change? I thought about doing that this weekend while I am home because I'm sure they haven't been replaced yet and thought that might help. So to compound the thread, what spark plugs does everyone run in these cars? I'm accustomed to NGK in the past, but doesn't mean I have to use them. I run TR-6s in my GTO and haven't had any issues yet.

TIA!
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Old 01-21-2010, 03:59 AM   #2
CKxx
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Your BOV sounds lame
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If it is drive-by-wire, then there isn't one.
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Old 01-21-2010, 10:32 AM   #3
arghx7
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does the car have any mods?
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Old 01-21-2010, 04:12 PM   #4
trbo_blu
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Originally Posted by arghx7 View Post
does the car have any mods?
No, it is completely stock. It did have an HKS blow-off valve on at for an unspecified amount of time (it came with the car).

And today I confirmed it is DBW and doesn't have an IACV...but still something is going on with the idling that I need to figure out. Its not something that is very frequent yet, but I'd still like to find the problem and fix it.
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Old 01-22-2010, 02:12 AM   #5
thunder_lizard_1976
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Try cleaning the Mass Airflow Sensor first (and make sure the plug contacts are tight), and if you're up to it, pull the I/C off, and clean the gunk off the throttle body/ plate as well. Do a reset, allow a few key cycles to do a relearn, and (hopefully) all should be well. Also check to make sure all your vacuum lines are intact/ secure, as that willl cause it to 'hunt' at idle as well.

As for the plugs, if the car is still stock, or even with minimal mods (intake, etc.), stick with the NGK's; There's no need to start mucking about with heat ranges/ materials until you get into heavier mods. I have found however with my own car, it does wonders for driveability to actually close the gap a few thousandths, iirc spec is .035, mine are set at .032. Because of the crappy stock tune, the 06-07's tend to literally 'blow out' the spark under high boost/ hard acceleration, and it seems to make cruising much smoother. The recommended interval is 60K; if you are daring enough to try and change them yourself, be especially wary of #4 (driver's side, rear)...I've been there, broke that, while trying to tighten it

Last edited by thunder_lizard_1976; 01-22-2010 at 06:19 AM.
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Old 03-25-2010, 08:41 PM   #6
IH8PVMNT
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Quote:
Originally Posted by trbo_blu View Post
I just picked up a 2007 WRX last week. The car does have 68K miles on it, but supposedly they are all highway miles. But anyways, at times during idle, it will drop down below 500 RPM and then surge up past 1200 or so RPM. It does it maybe once or twice a day randomly while sitting at a stop.

I did a search on idle issues and came across several posts recommending that the Idle Air Control Valve be taken off and cleaned as dirt and oil buildup can occur inside and cause idle issues. I was going to order a gasket to make sure I could replace it after taking off the valve.

However, I found a post which I can't find it now that someone had said the 07 didn't have a IACV. Its dark outside and I don't have a flashlight here at my apartment to go out and take a look to see if I see it or not. So my question is, was that a legitimate post or does the 07 WRX have a IACV?

If it does not, what other recommendations do you have? It hasn't thrown a code and doesn't do it that often. When does Subaru recommend a plug change? I thought about doing that this weekend while I am home because I'm sure they haven't been replaced yet and thought that might help. So to compound the thread, what spark plugs does everyone run in these cars? I'm accustomed to NGK in the past, but doesn't mean I have to use them. I run TR-6s in my GTO and haven't had any issues yet.

TIA!
haveing the same problem!!! surge in idle is drving me crazy, also have a 06 wrx.... did you find anything ?
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Old 03-25-2010, 08:51 PM   #7
fast06wrxtr
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Quote:
Originally Posted by trbo_blu View Post
I just picked up a 2007 WRX last week. The car does have 68K miles on it, but supposedly they are all highway miles. But anyways, at times during idle, it will drop down below 500 RPM and then surge up past 1200 or so RPM. It does it maybe once or twice a day randomly while sitting at a stop.

I did a search on idle issues and came across several posts recommending that the Idle Air Control Valve be taken off and cleaned as dirt and oil buildup can occur inside and cause idle issues. I was going to order a gasket to make sure I could replace it after taking off the valve.

However, I found a post which I can't find it now that someone had said the 07 didn't have a IACV. Its dark outside and I don't have a flashlight here at my apartment to go out and take a look to see if I see it or not. So my question is, was that a legitimate post or does the 07 WRX have a IACV?

If it does not, what other recommendations do you have? It hasn't thrown a code and doesn't do it that often. When does Subaru recommend a plug change? I thought about doing that this weekend while I am home because I'm sure they haven't been replaced yet and thought that might help. So to compound the thread, what spark plugs does everyone run in these cars? I'm accustomed to NGK in the past, but doesn't mean I have to use them. I run TR-6s in my GTO and haven't had any issues yet.

TIA!
This sounds like what my car does after I reset the ECU. If the battery was pulled recently, it will do it for a hundred miles or so until the computer learns a bit.
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Old 03-29-2017, 12:01 AM   #8
Luke_Duke2006
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Quote:
Originally Posted by IH8PVMNT View Post
haveing the same problem!!! surge in idle is drving me crazy, also have a 06 wrx.... did you find anything ?
I have a 2006 wrx as well having a similar issue. It'll huntvat idle and throws a lean code. I've noticed it does it to me more when it's warm and left at idle for like 3 minutes. Upon cold start the TGVs are richening the fuel mix to bring the engine to temp and as they open the air flow begins the lean the AFRs. Normal running/cruising I see 14.5-14.7 ratio then upon decell 20.4 and upon accel or boost 11.0-11.2 which is normal but only at idle does it sit around 16.3-18.0, I've replaced upstream O2 sensor, intake gaskets, sealed all exhaust leaks, replaced the air inlet that had a hole in it I assumed was the source of the unmetered air, I even borrowed a evap smoke machine to smoke my intake system to check thoroughly for leaks; found none. So for my particular issue (which sounds similar to your all's) it's gotta me some sort of sensor. I have adequate voltage out of my MAF. Running out of ideas where to look. Thanks for reading let's solve this together!
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Old 03-29-2017, 02:28 PM   #9
winston856
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Alright guys, I have an easy resolution for you to try. I had a similar issue where the idle would hunt but it would NEVER do it with the hood open. When the hood was closed the issue would present itself.

For me it was the stock airbox that was not fully seated. I. kid. you. not.

Go out to your car open the hood, look down at the stock intake box.

Notice the two metal snaps at the front (top), notice the 2 black plastic tabs at the rear (bottom). For me it's always a bit of a wrestling match but those tabs have to be fully seated / clicked into their receptors.

It is possible to put the box on with those tabs sitting on top of the slots they're designed to go inside.

I have found if you angle the intake lid downwards to slide those in then clip the metal tabs last to be the best way to make sure they're fully seated. Even then I have to wiggle the lid a bit to get them to seat fully.

Make sure they're not cracked / broken.

After I did this, no more idle hunting or lean AFRs.
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