Rough Idle? (possible easy fix)?

Hey guys so i started my car after being up at Mt Ruapehu for the weekend and let it warm up before i drove anywhere, but as i got into it after packing i noticed the engine like kicked and the revs rise then drop suddenly then pick up again as it reaches below 500rpms (sort of dissmissed it thinking it was just the cold getting to the engine or something). Today i started her up and as it was warming up i noticed it doing the same thing but this time i could feel the engine almost like kick as if it was misfiring on a cylinder possibly??

I was wondering if anyone else has had this problem or would know whats causing this as im not that mechanically inclined about engines.

(sorry for the long post)

Cheers

Dean

Sounds like a sticky IACV (idle air control valve), might need a clean out. Maybe a slight vacuum leak somewhere. Does it only ever do it when cold?

Nah it does it when its warm too i just noticed it was doing it while warm yesterday arvo.

And how would i go about cleaning the IACV?

What model legacy is it?

its a 2007 BL5.

I was wondering if an ecu reflash would help at all?

Oh, check no vac hoses have popped of, or perished and split. I'm not familiar with the newer legacy's but don't think they even have an IACV? Has the CEL ever come on?

Possibly a gasket/o-ring leak between the manifold and TGV bodies, could try spraying ether/engine starting fluid around the base of the manifold when cold to see if the idle changes.

Have a read through this:

http://legacygt.com/forums/showthread.php/diy-rough-idle-cold-start-cold-temps-lgt-07-09-155325.html

No CEL so far, from the link i have a feeling it might be that but doesnt sound as bad as they are describing on their cars (probably because its alot colder there lol).

Can't really do anything to the car other than take it to a mechanics as i don't have any tools or space to pull the car apart in Hamilton.

would i do that whilst the car is running?

Yes, should make an instant change to how it's running.

Do you guys have like a step by step on how to do this as i dont have a clue about engines.

http://www.uklegacy.com/forums/index.php/topic/128159-how-to-idle-re-learn-after-battery-disconnect/

Try this dude, I did it yesterday and it did wonders for my 1999 Legacy

Awesome find man thanks a bunch am going to do this after i change my oil on thursday

That link is for resetting a wondering idle air control valve, so probably won't do much for a 2007 BL5.

Chances are you have a vac leak, fouled plug, bad coil, dirty injector, leaking manifold O-ring, carbon build up in the TB or a bad sensor (O2/AFM/TPS/coolant etc).

If you're not really mechanically inclined at all (and it sounds like you aren't) you could spend a long time chasing your tail from internet advice

Does this problem only happen when the car is cold? Is it behaving fine otherwise (such as power, gas usage etc)?

As has been said it could be any number of things to cause this problem, it could be a sensor issues (such as the airflow meter, the temp sensor, even just the calibration of the throttle itself?) or a physical issue in the form of something not firing, not opening as it should, or something perished. On a car this relatively new I'd be thinking it's unlikely that parts are perishing unless it's had a particularly hard time of it?

My advice would be take it to someone or somewhere who can at least plug a scanner into it, it may not have a "check engine" light on but a misfire on a car that new should still trigger a code for something out of the ordinary. Worst case I have had cars get left overnight just so the issue can get diagnosed by someone with the tools to actually diagnose it, could be a lot simpler than trawling through a dozen different avenues

wait... ross said most of that already haha

 Marky said:

If you're not really mechanically inclined at all (and it sounds like you aren't) you could spend a long time chasing your tail from internet advice

Does this problem only happen when the car is cold? Is it behaving fine otherwise (such as power, gas usage etc)?

As has been said it could be any number of things to cause this problem, it could be a sensor issues (such as the airflow meter, the temp sensor, even just the calibration of the throttle itself?) or a physical issue in the form of something not firing, not opening as it should, or something perished. On a car this relatively new I'd be thinking it's unlikely that parts are perishing unless it's had a particularly hard time of it?

My advice would be take it to someone or somewhere who can at least plug a scanner into it, it may not have a "check engine" light on but a misfire on a car that new should still trigger a code for something out of the ordinary. Worst case I have had cars get left overnight just so the issue can get diagnosed by someone with the tools to actually diagnose it, could be a lot simpler than trawling through a dozen different avenues

wait... ross said most of that already haha

The car runs fine when im driving and havent noticed anything out of the ordinary with fuel usage, but i have noticed that it does it when the car is warm.

I have enquired with some mechanics but they either dont have a clue about subarus or they dont have the tools to check (i must be enquiring with the wrong ones hah) someone point me in the right direction with who i could take it to either in hamilton or bay of plenty? Please and Thank you

I'm going to give the idle re learning a go anyways cant hurt to try that.

It's worth a try, for what? 40 minutes of your time? And it can't hurt. Nothing tried nothing gained

 B4 I was 250T said:

It's worth a try, for what? 40 minutes of your time? And it can't hurt. Nothing tried nothing gained

Exactly haha Well said

sounds more like a blocked vvt solenoid or faulty injectors. try cleaning out the vvt solenoid first as the oil feed bolt houses a strainer that breaks off overtime and gets stuck in the vvt solenoid which advances the cam timing to more than 50 degrees on idle. if you in auckland than come and see me, ill sort it out for you.

 subirex said:

sounds more like a blocked vvt solenoid or faulty injectors. try cleaning out the vvt solenoid first as the oil feed bolt houses a strainer that breaks off overtime and gets stuck in the vvt solenoid which advances the cam timing to more than 50 degrees on idle. if you in auckland than come and see me, ill sort it out for you.

Where abouts are you in auckland? it would be awesome if you could help me out and possibly teach me some things about my engine haha

 subirex said:

sounds more like a blocked vvt solenoid or faulty injectors. try cleaning out the vvt solenoid first as the oil feed bolt houses a strainer that breaks off overtime and gets stuck in the vvt solenoid which advances the cam timing to more than 50 degrees on idle. if you in auckland than come and see me, ill sort it out for you.

This is your first port of call. Car will seem to drive normally but idle like balls.

Very easy to check. Undo the VCT solenoids, one on each bank, and check for filter debris stuck in them. Remove debris and the problem will be sorted.

There are a few how to pages around the place.