Did I Just "Reset" the PCV Valve ?

[LoneRanger]

Been chasing a rough idle on my Subaru,and idle speed about 100rpm lower than spec. No vac hose problems found and the brake booster passes the usual tests.

Pulled the PCV hose off the intake nipple and blocked nipple w/ my finger, idle didn't seem to improve much. Have to be quick reconnecting the hose because it almost stalls as expected when taking finger off the nipple. Connected it up and the idle was now better and upon checking the tach it was back up to spec and seemed to be staying there.

Could the PCV have been stuck and pulling off the vac source cause it to reset or something?

This probably means I need to replace it. Not a simple job on the Subaru. But I'm hoping this is the culprit.

 

[sicko]

Like you said, probably means you need to replace it. Kind of surprising considering it's only an '09.

I haven't changed the PCV on my '09 Forester yet, but when I looked up how to do it, it didn't seem that difficult. Have you looked at any of the guides for your model Subaru? Do you have a shop manual?

 

[LoneRanger]

Looks like the ignition coil will have to come off to get a ratchet w/ extension on the PCV. And going to take a deep well socket which I'll need to find out the right size.

Agree about an '09. Only 43,500 miles. Prior to this year it has been a garage queen usually only getting out on weekends. Infrequent use does breed problems sometimes, though.

 

[gregk24]

Originally Posted By: LoneRanger
Been chasing a rough idle on my Subaru,and idle speed about 100rpm lower than spec. No vac hose problems found and the brake booster passes the usual tests.

Pulled the PCV hose off the intake nipple and blocked nipple w/ my finger, idle didn't seem to improve much. Have to be quick reconnecting the hose because it almost stalls as expected when taking finger off the nipple. Connected it up and the idle was now better and upon checking the tach it was back up to spec and seemed to be staying there.

Could the PCV have been stuck and pulling off the vac source cause it to reset or something?

This probably means I need to replace it. Not a simple job on the Subaru. But I'm hoping this is the culprit.


It could be that its gunked up. You could try cleaning it, but like you said if its a difficult job you might as well just put a new one on there.

Edit: If you choose to replace it, I suggest going OEM. I chose to use a Napa PCV valve on my Accord, it was metal and looked to be of good quality but it buzzed and clicked. I then ordered an OEM valve and the noise ended.

 

[oldmaninsc]

Yeah I agree, I've never had good luck with aftermarket valves. I always use OEM for that.

 

[qdeezie]

For what it's worth, on vehicles with a PCV that I own, I spray out the PCV out with brake cleaner and soak it in Acetone every oil change. This keeps me from ever having to replace it (after purchasing an OEM unit).

 

[gregk24]

Originally Posted By: qdeezie
For what it's worth, on vehicles with a PCV that I own, I spray out the PCV out with brake cleaner and soak it in Acetone every oil change. This keeps me from ever having to replace it (after purchasing an OEM unit).


I bet that puppy stays clean! I would just rather slap in a new OEM valve every 60-100K and be done with it.

 

[qdeezie]

Originally Posted By: gregk24
Originally Posted By: qdeezie
For what it's worth, on vehicles with a PCV that I own, I spray out the PCV out with brake cleaner and soak it in Acetone every oil change. This keeps me from ever having to replace it (after purchasing an OEM unit).


I bet that puppy stays clean! I would just rather slap in a new OEM valve every 60-100K and be done with it.


You save more money doing it this way and if your PCV is easy to access, it's not a headache at all. I've soaked my PCV quite a few times doing it this way and the acetone is still crystal clear.

Even if you did it every 2 or 3 oil changes, your PCV would still be clean.

You'll probably chuckle (or shake your head), but I repurposed a plastic Talenti Gelato container to be my PCV acetone soak container. Works like a charm and if it were to fall on the floor, I don't have to worry about it shattering.

The acetone was $2.50 and the container was free, so it's is a pretty economical setup.

 

[ARCOgraphite]

LR -Maybe just drizzle a 1/2oz kerosene down there for an couple hours - likely just gum.. Should be metal pill in metal not much to wear out. This engine has 2 breather hoses (IIRC) make sure they are free and clear, too.

 

[ironman_gq]

Sounds like it's a perfect candidate for PCV problems, infrequent use and short trips leads to moisture buildup which in the PCV turns to sticky crud causing them to stick. I'd pull it off and give it a soak in mineral spirits and blow it out with brake cleaner. Or replace it, they are usually pretty cheap.

 

[05LGTLtd]

Earlier foresters were simple to get at the PCV valve. This one is about middle of the road. Get an air filter and a can of maf cleaner since you will be right there. Once you pull the coil pack the PCV valve just lifts out. Why subaru decided to put it right on the block is a mystery to me. PITA to change, comparatively, and more likely to gunk up.

If you get the NAPA one, you will need a vise to swap the valve off the housing.

Average shade tree mechanic should allow an hour for the job. Level of difficulty: one beer reward.

 

[LoneRanger]

Changed it out tonight. Did not have to pull ignition coil, just had to pull the plug boots off the #2 and 4 side. Used permatex non-hardening high temp thread sealant (not locker) on it. Took a 19mm deep well. Not too bad of a job. I'll know tomorrow if it helped. Probably need to do another idle re-learn process on it with the new valve in now.