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2003 Forester 2.0 XT 5MT
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259 Posts
Discussion Starter · #1 ·
From sometime ago my Forester started to increase the idle when I was in heavy traffic. The hotter the car gets, the higher the idle. It even reached 2700 rpms! If I'm not in traffic the idle is ok. It only happens under heavy traffic where I have stop & go constantly. If I tap the accelerator the idle returns to normal rpms, but if the traffic moves and I move the car a bit, the idle will increase again.

I followed the thread on Nasioc on how to clean the Idle Air Control Valve but this made no better to solve the problem. After sometime it started to idle high with the car being cold and then the CEL came in showing the error code for the idle control valve so I decided to get a new valve.

I recently installed the new valve, but the problem keeps the same! The CEL went off but it keeps idling high under heavy traffic, and as with the old one, the longer the time I'm in the traffic, the higher the idle becomes. It is working perfectly with the car being cold.

Thanks for the help.
 

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2002 Forester L 5 Speed
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203 Posts
Sounds like a vacuum leak. Try tracing all of the vacuum lines under the hood and see if you can find a broken hose or poor fitting connection.

Alternatively, could be a grounding issue. Try disconnecting your grounds, clean the posts, and reconnecting them.

Good luck!
 

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Registered
2003 Forester 2.0 XT 5MT
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259 Posts
Discussion Starter · #4 ·
Sounds like a vacuum leak. Try tracing all of the vacuum lines under the hood and see if you can find a broken hose or poor fitting connection.

Alternatively, could be a grounding issue. Try disconnecting your grounds, clean the posts, and reconnecting them.

Good luck!
Ok thanks. I'll check that. However I find hard to believe that a vaccum line is causing the problem. If the problem was a vaccum line, then tapping the accelerator will not lower the rpms. I'm leaning more to an electrical problem so I'll check the groundings.
 

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2003 Forester 2.0 XT 5MT
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259 Posts
Discussion Starter · #6 ·
Any luck tracking down the issue?
Searching online I read that the MAF sensor could be a cause. I cheked it it and it seemed to be covered with dirt, so I used en electronic cleaner can to spry the MAF. I was able to see that not all dirt came off but I left it that way as I read also that one should not touch anything on the maf sensor.

Before the cleaning my idle started to go up after 10 or 15 mins in heavy traffic. After the cleaning it took more than 40 minutes of heavy traffic before it started to go up again.

So in conclusion, the maf sensor is my problem. Perhaps if I'm able to completely clean it I guess the issue will be fully solved, so I'll probably get a can of Mass Airflow sensor cleaner which I assume is better than just an electronic cleaner. Or maybe they are the same and they just change the graphics on the can.
 

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From sometime ago my Forester started to increase the idle when I was in heavy traffic. The hotter the car gets, the higher the idle. It even reached 2700 rpms! If I'm not in traffic the idle is ok. It only happens under heavy traffic where I have stop & go constantly. If I tap the accelerator the idle returns to normal rpms, but if the traffic moves and I move the car a bit, the idle will increase again.

I followed the thread on Nasioc on how to clean the Idle Air Control Valve but this made no better to solve the problem. After sometime it started to idle high with the car being cold and then the CEL came in showing the error code for the idle control valve so I decided to get a new valve.

I recently installed the new valve, but the problem keeps the same! The CEL went off but it keeps idling high under heavy traffic, and as with the old one, the longer the time I'm in the traffic, the higher the idle becomes. It is working perfectly with the car being cold.

Thanks for the help.
where is the idle air control valve located on the 2004 subaru forester xt?
 
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