High idle, and check engine light on.
 

Hi guys, got a bit of a query I wonder if you can help me with please?

The car is a Subaru Impreza Wrx Sti 2005.

What is happening is that out of nowhere, the car has suddenly decided to idle at about 1600-1700 revs, when it used to idle at about 600. The check engine light has also come on. Also, if I drive the car (which doesn't feel good at all), the revs will bounce between 800-2000 for no reason, and coming to a half the car almost stalls before idleing highly again.

I did a bit of research, and what I found is that it could be a faulty MAF sensor, so I replaced this, and it didn't make any difference.

I also found that it could be the Air Intake Control Valve, so I took this off and cleaned it, reinstalled it, but that also didn't make any difference.

Is there anything else I can try before I take the car to a professional? I'm trying to save a bit of cash by doing it myself, and also trying to learn at the same time!

Would appreciate any ideas and thoughts!

Cheers,

Chris.

Buy a code scanner such as this one...


...which will tell you the fault code which has triggered your check engine light which will narrow down the possible cause of the trouble and will come in very handy in the future.

Thats great, cheers, I've just bought one, and I'll report back with the error code once it has arrived.

I'll also try to fix it depending on what error code it is!

Thanks again!

Well I managed to get hold of a code reader, and it is throwing up P0519, which is the air intake control valve.

I've already tried cleaning it, so I guess I'm going to have to open it and take the motor out and clean that. If not, I'll have to buy a new one.

Does anyone know if this one from eBay ( http://www.ebay.co.uk/itm/80Q-For-Su...item3ce9d500fd ) will fit an 05 model? It says is is an 02-04 model, but sometimes these things work on other models?

That's the correct one

Thats great, cheers, I'll get it ordered!

Thank you :)

Don't know if you have seen this guide but may come in useful for you.

Cleaning And Reattaching The IACV (Idle Air Control Valve) - NASIOC

Hiya, yes I saw the guide so I had a go - it didn't make any difference so what I did was bought a Torx screwdriver and opened up the I.A.C.V. It seems that the bearing that the motor attaches too was reasonably/quite stiff, and doesn't run like a normal bearing does, free and easy. Is this right, or has it seized?

The car is still throwing up the P0519 (Idle Air Control Valve) error - although since cleaning it thoroughly the car drives, just about, whereas it was undriveable before.

I think the valve (or stepper motor inside) is still at fault - I've taken a video to show that when the car is cold it idles at 1500 revs, but when it warms up, it rises to 1750 or so.

https://www.youtube.com/watch?v=bEv0...ature=youtu.be

Does anyone else think that this is going to be a IACV replacement needed?

Cheers for now!

Chris

Out of interest, I took the idle control valve off, split the motor and the valve, put a drill bit on the bearing shaft and revved the hell out of the drill, spinning the bearing and valve in the process.

Refitted it into the car, and it is now revving at 1200rpm when warm, instead of 1750. As far as I can see that definitely indicates a faulty valve.

Replacement time I think!

I have the same problem, on the same model and year (spooky)... did you get it sorted?

Any advice would be appreciated as Subaru want £372.43 for a new one....

Cheers,

Chris.

Hiya mate, yes, I fitted a new valve which I got off eBay for £40, and instantly the problem was fixed.

I reset the "check engine light" using a code reader, and that was the end of the problem.

Whats yours doing then? Just revving highly, and then almost cutting out when you drive up to a junction?

Sort of... it's revving high, hunting from about 1400 - 1900 rpm, then sort of settles a bit.. no cutting out yet though! Cleaned the valve out today and fitted new gasket, no change, got the local garage to check out the code (P0519).... sounds very similar to yours, I've just ordered another valve (used), so hopefully sort the problem!

I'm pretty sure that will sort it - in the meantime if you have a 5 point torx screwdriver, you can split the valve and the motor, attach a drillbit to the valve, and spin it - put the valve and motor back together, and reattach it to the car - I'll bet you it makes the car idle a bit less, and maybe even fixes the problem!

Where did you get your second hand valve from?

I got it off mattyb on here, he's currently breaking an 05 sti. The idle isn't too bad yet, so will live with it unless it gets really bad. Once I've got the new one I'll take it apart and see what can be done.... where did you get your 5 sided torx? I've only ever seen 6 sided ones!

I'm pretty sure I got this one here: http://www.ebay.co.uk/itm/Trident-T1...item337e3234a8

I've started getting a decent toolset together now, as I found one of the major problems I came up against was not having the right tools (due to never having worked on a car before).

Just buying things bit by bit, and its not too expensive that way.

I've just ordered some, I'll see what I find.... might turn out ok?! Have a feeling it'll probably be knackered though!