Locate the idle air control valve. On a '99 Legacy 2.2L, it is on the driver's side of the throttle body. The factory part will have a blue sticker on it giving the part number (A33-661 R02).
The valve is held on by two screws which have a reputation for mushing to pieces under the force of a poorly placed screwdriver, so make sure you have the right size (use a flat-head, not phillip's) make sure you have a very firm grip and plenty of pressure on the screw head.
I found all kinds of black gunk on the tip of the valve. Before cleaning it off, leave it plugged in to its wiring harness and lay it on the engine in a place where you'll be able to see it from the driver's seat. Turn the ignition key to the 'on' position (not start): the tip of the valve should move in or out, and back again when you turn the key off. If you don't see any movement, then it's likely your valve it either way too gummed up or, worse, the electrical/mechanical components inside have failed. Either way, you'll want to clean it up and try again.
Before cleaning, I removed the rubber O-ring from the valve (you don't want the cleaning agents to degrade the rubber). Next I used carburetor cleaner, rags and Q-tips to thoroughly remove all deposits from the valve. In the process, the spring and seating parts came out of the solenoid - I'm not sure if that is supposed to happen, but I was able to put them back in without problems.
With the valve removed, I also cleaned the air passages in the throttle body which also had plenty of black gunk.
My IAC valve was shiny-clean, so I replaced the O-ring and plugged it back in to the wiring harness to test it. I turned the ignition to the on position and it appeared to move in & out much more freely than before.
After ensuring that all parts were clean and dry, I re-installed the valve. Also, ensure that you have correctly replaced the air box, and that all other air intake components you may have removed are tightly reconnected.
Voila - it again idles smoothly.
Typically, an IAC valve goes bad by fouling, like mine did. However, they can also fail electrically or mechanically. Check for voltage in the wiring harness and continuity between the pins on the solenoid itself. I rule out mechanical failure by cleaning thoroughly and observing actuation of the solenoid when turning the ignition to the 'on' position.
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ReplyDeleteI wish I'd read Nathans' comment before trying the testing method outlined above.
ReplyDeleteMy Idle control piston & spring also shot out of the barrel at high speed during testing, the barrel hit the inside of the engine bay, fell down and was retrieved but the spring is nowhere to be seen.
Please DON'T try the test method above (Ignition on and off to push piston out and in) unless you have a small bucket with a soft rag inside it rigged up to catch the piston if it flies out!
Hello,I also wish I'd read Nathan's comment before testing my IACV.Fortunately I found both of the details,but how to put them back.I tryd with ignitition on and off same time pushing to the piston several times.Anyway it stayd too far from right position.Please tell me,how to put them in right place.
ReplyDeleteI am working on this issue myself. My 2003 Impreza Outback has a new long block, with Six Star Head Gaskets, and the rest of the engine has 216,000 miles on it. I took the Idle Control Valve out, and put in an inexpensive replacement that is more compatible with an Impreza RS. For a few days it worked fine, but then, I had the same trouble keeping idle. I cleaned out the old one, soaking it in Seafoam, and today, I bought Throttle body cleaner, and removed the ICV, and sprayed into the opening, along with wiping the area out as well as I could. I put the original part back in, and it took a bit, but it started back up. I plan on using heavy doses of Seafoam into my gas for a period, to help clean up the system. If the valve is giving me trouble, I can order a less used one on E-bay for under $100. They told me at O'Reilly's that the Seafoam should take care of the problem over the next dew weeks. I have a 5 speed, so it longer for the carbon to built up, because it runs on higher RPM's more often. If you need a long block, go to Ebay, and find SSi Subie Specialists. They having amazing deals, and the engines are better than factory, because the head gasket issues are addressed correctly. The saved me $2,000.
ReplyDeleteJust did all of the above yesterday myself. All you need is another person to turn the key on/off for you while you hold the IAC valve in one hand and press the valve on top with finger. Thus you won't fire the valve and the spring.
ReplyDeleteDo try to remember the position of the valve when removed from the body. The way you had it out is the way you should install it back.
The IAC valve is a solenoid with motor. By soaking the whole IAC valve in carburetor cleaner for a long time (or other degreaser) you might "clean" the barrel inside, which you don't really want to happen. You need the whole valve well cleaned from deposits but, you need the barrel inside greased (not oiled) for smooth motor operation.
When I had the valve cleaned and the motor greased, I tried to assemble both pieces. By having someone else turning the key on/off, you should slightly press the valve. Not just hold it not to fire, but actually press it a little so the motor could "eat" the valve. I had to do this several times as first time when I had the valve attached to the barrel, and the complete IAC valve installed back in the intake manifold, I had the engine idling at 1500 rpm. Second time I had it idling at 1100 rpm. And third time I had idling at about 600-700 rpm, which is what I needed for my 2003 EJ25 Outback.
By the time I was trying to adjust the IAC valve so the engine could idle at 600-700 rpm, the ECU throw a cell (check engine light came out). After self-diagnostic and cleaning the error, I never had it back and, I had my engine idling just perfectly.
Worked perfectly for me. My idle was non-existent (start the car, and unless revs were manually kept up it would drop to zero and obviously stall), this has so far fixed the problem. There was A LOT of carbon built up. Kerosene did the job. Thank you!!
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ReplyDeletedo you know the part number for the o ring?
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ReplyDeletethanks for this explanation - I'd ask the same question at Unknown on Mar 28 - what is the part number for the o-ring?
ReplyDeletewow - sorry - just did a bit of searching, and found this -
ReplyDelete1. IACV to TB gasket part# is 22659AA120
2. O-ring Motor to housing Size: 3/4ID, 7/8OD, 1/16 wall