My 02 Outback when cold (regardless of the outside temp) will rev up to 3,000 and hold it there. The only way I can get the revs to drop is to put it in gear or just neutral and let the clutch out. Everything else is running fine. I just don't even know where to start looking. It does this longer when its colder out, but will do it in all temperatures. Its just a bit annoying driving in the city, because at every stop its revs up so high.

Thanks for any help!

Sounds like a sticky idle air control valve. On cold mornings, as normal operation, the car can idle that high, until it begins to warm up.

 

There is also a temp sensor on the back of the intake that tells the computer how warm the car is. If it is bad, the car can think it's too cold when it is actually warm, and holding the idle up by manipulating the IAC as if it were cold.

I think some of the MT's of that era also had trouble with the switch that told it if it is in gear or in neutral. But I believe that normally threw a P15nn something like that code. Also not sure if that would cause that wide of a idle variation. Do you have a check engine light on at all?

I think some of the MT's of that era also had trouble with the switch that told it if it is in gear or in neutral. But I believe that normally threw a P15nn something like that code. Also not sure if that would cause that wide of a idle variation. Do you have a check engine light on at all?

 

 

It would

Hmmm... My 2001 3.0 does this as well, I was told, by "someone on here" that "that's what Subarus do"...

Sounds like a sticky idle air control valve. On cold mornings, as normal operation, the car can idle that high, until it begins to warm up.

 

There is also a temp sensor on the back of the intake that tells the computer how warm the car is. If it is bad, the car can think it's too cold when it is actually warm, and holding the idle up by manipulating the IAC as if it were cold.

 

Would this show a code????

the check engine light isn't on, but the neutral switch isn't too much money, that's probably the 1st thing I'm going to swap out. Any suggestions on cleaning the IAC? I've read a few threads on that, and not quite sure how to proceed. (this is my 1st subaru after a long affair w/ VW so I'm still fairly lost on this engine)

My 2000 Legacy with MT does the same thing after a cold start…..was fine during spring and summer weather but now that it's getting chilly, it happens every time.

Could someone post pictures of where the idle air control valve and temp sensor are located?

Can they be effectively cleaned?

the temp sensor may just have some corrosion on the terminals, but it's a good idea to replace it as the parts are not hard to find or expensive at all. The engine temp sensor has a reddish borwn connector and is located at the back of the intake just under the throttle body.

 

The idle air control valve is located near the throttle body. You can try filling the hose up with sea foam and let it soak overnite to free it up. Or you can remove it and disassemble and clean with carb cleaner.

 

It wouldnt throw a code unless it was broken or had an electrical failure. If it is sticky, the computer could think its closed, but it's hanging open.

 

think of the idle air control valve as the choke on a fuel injection.

I think some of the MT's of that era also had trouble with the switch that told it if it is in gear or in neutral. But I believe that normally threw a P15nn something like that code. Also not sure if that would cause that wide of a idle variation. Do you have a check engine light on at all?

 

A CTS will not throw a code unless it is completely open or shorted, otherwise everything inbetween looks like a normal function.

thanks for the help and advice. I put in a new coolant temp sensor, cleaned the throttle body, pulled and cleaned the IAC and the high rev problem went away... for 3 days and now its still doing the same thing. When its cold, push in clutch and revs bump up to 3k, let clutch out (in gear or neutral) revs drop back down. Once its warm it idles just fine. thoughts?

What condition was the Iac valve in? A lot of junk? Since it was fine for three days I think your on to something. Iac valve might still be sticking or trash. I soaked mine in gasoline ovenite. Looks and works like new. Also, good idea to get a new gasket fron the dealer.

similar problem on an AT, cleaned throttle and temp sensors, haven't done iac. only revs to like 2k, but that's a bit high for normal, isn't it?