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Old 04-22-2021, 11:39 PM   #1
cproo12
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Default 06 FXT 5mt - Rough Idle only when warm (Ringlands??)

Hi, I am working on diagnosing a problem I just started having on my 06 Forester XT after a long (375 mile) highway drive. Rough idle, only when hot.

I just bought this car in January, and while I had a naturally aspirated boxer before, I am new to the turbo EJ25 and problems it involves.

The car has 185k on it, and as far as I know, the engine has never been torn into for anything. Only mods: STi intercooler, grimmspeed downpipe, invidia q300 catback, GFB BPV, wideband O2 sensor in the downpipe, and some stereo stuff.

I check my oil every time I get gas. I have to fill with probably half a liter every other tank of gas. Car has ran perfectly fine (up until now)

I drove downstate and back, just highway driving at 85-90mph, had it around 4k RPM the whole time, and now I am home and when I start the car, idles with vibration, but nothing crazy, then after it warms up, really starts to shake side by side like a misfire.

One CEL (P0153 Fuel Evap Pressure High).

I think it is the piston ringlands beginning to fail, causing low compression in one cylinder (probably 4)

Any suggestions welcome. I am comfortable working on cars, but have never worked on a DOHC, only the EJ253 in my old forester. I can afford to rebuild the motor, but obviously need to try cheaper fixes beforehand.

I am not driving the car at the moment, scared of completely blowing out a ringland and ruining the cylinder wall.

EDIT: Here is a youtube video of me showcasing the vibrations and that there does not seem to be a crazy amount of air coming out of the oil fill.

Last edited by cproo12; 04-22-2021 at 11:40 PM. Reason: added video link
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Old 04-23-2021, 12:30 PM   #2
K3rm1tth3fr0g
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Check if there is smoke coming out of your dipstick tube/oil fill cap when the car is warmed up and running. If there is, it's toast.

Last edited by K3rm1tth3fr0g; 04-23-2021 at 01:55 PM.
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Old 04-23-2021, 01:42 PM   #3
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Quote:
Originally Posted by K3rm1tth3fr0g View Post
Check if there is smoke coming out of your dipstick tube when the car is warmed up and running. If there is, it's toast.
You'd have seen it coming out of the oil fill cap. Ask me how I know...

https://www.subaruforester.org/threa...-oh-no.679530/

OP I would put some new OEM plugs in it and do a compression test while you're swapping them out.
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Old 04-23-2021, 01:55 PM   #4
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Quote:
Originally Posted by pigboat_2 View Post
You'd have seen it coming out of the oil fill cap. Ask me how I know...

https://www.subaruforester.org/threa...-oh-no.679530/

OP I would put some new OEM plugs in it and do a compression test while you're swapping them out.
Thanks. Hoping this solves my problem. I am gonna be soooo sad if I have to have a shop rebuild my engine. Reeeally wanted to do that myself in a few years

Waiting for video of oil fill to upload. I have prehistoric internet upload speeds.

There is a very small amount of smoke/vapor coming out of it, but I can barely even see it. I think it is just water boiling off the oil, but too scared to go for a drive and get oil up to temp...
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Old 05-18-2021, 11:45 PM   #5
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Quote:
Originally Posted by pigboat_2 View Post
OP I would put some new OEM plugs in it and do a compression test while you're swapping them out.
Tried to tell ya...

Let us know what you find.
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Old 04-23-2021, 05:44 PM   #6
cproo12
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Here is a youtube video showing the oil fill in direct sunlight.

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Old 04-23-2021, 06:04 PM   #7
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when I had those same symptoms it was because valve clearances had become too tight. it only caused rough idle after a long drive when everything was hot... otherwise it would run quite smooth.

it could be something else, but wanted to share my experience.
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Old 04-23-2021, 06:22 PM   #8
cproo12
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Quote:
Originally Posted by heiche View Post
when I had those same symptoms it was because valve clearances had become too tight. it only caused rough idle after a long drive when everything was hot... otherwise it would run quite smooth.

it could be something else, but wanted to share my experience.
So that would be timing belt tension, right? I have a timing belt kit, but was waiting to put that on until I rebuilt the engine.
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Old 04-23-2021, 07:49 PM   #9
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in my case it required different sized valve buckets, which is how you adjust the valve clearance. the timing belt is separate. again, valve clearance issue might not be the same for your case, but it was for me.
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Old 05-04-2021, 01:11 PM   #10
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Quote:
Originally Posted by heiche View Post
in my case it required different sized valve buckets, which is how you adjust the valve clearance. the timing belt is separate. again, valve clearance issue might not be the same for your case, but it was for me.



I suffered the same. Theory is the valve stems may elongate while hot. And if the clearance is already tight to begin with, it will then get worse when the engine is hot, thereby loosing compression. I was always registering misfires at idle on a specific cylinder when warm but not really when cold. And lo and behold, the valve clearance was in fact super tight on one exhaust valve. If it is the case and you wait too long, then the valve will burn.


In general, my understanding is that if the rings were bad, then it would be even more noticeable at cold idle since the rings have not had time to expand with heat. Compression should return when warmed up even with cracked ringlands, unless really bad.


In any case, before spending any 'real' money, you could always check your valve clearance first. Pretty easy job. It will cost you new valve cover gaskets, some rtv and your time.


If clearance is good, then leakdown test would be next.
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Old 05-04-2021, 04:55 PM   #11
cproo12
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Quote:
Originally Posted by enduroxt View Post
I suffered the same. Theory is the valve stems may elongate while hot. And if the clearance is already tight to begin with, it will then get worse when the engine is hot, thereby loosing compression. I was always registering misfires at idle on a specific cylinder when warm but not really when cold. And lo and behold, the valve clearance was in fact super tight on one exhaust valve. If it is the case and you wait too long, then the valve will burn.

In general, my understanding is that if the rings were bad, then it would be even more noticeable at cold idle since the rings have not had time to expand with heat. Compression should return when warmed up even with cracked ringlands, unless really bad.
That totally makes sense. I was thinking along the lines of, the vehicle is warm, the oil is less thick, there is no seal along the rings. When oil is cool, being thicker, it seals the rings, but this makes more sense. Thick oil wouldn't contain an entire combustion.

Quote:
Originally Posted by enduroxt View Post
In any case, before spending any 'real' money, you could always check your valve clearance first. Pretty easy job. It will cost you new valve cover gaskets, some rtv and your time.

If clearance is good, then leakdown test would be next.
Good news is I already have a bunch of stuff to put on this engine. (Valve cover seals, half moons, front/rear camshaft seals, front main seal, water pump, and all timing components).

I am just waiting for the weather to warm up because my "auto shop" consists of my gravel driveway.

Currently awaiting a spark plug socket in the mail then going to do my spark plugs and test compression. I don't have a compressor to do leakdown, but will take it to a shop to do that if its not the spark plugs, coils, or valve to valve.

Thank you for the informative comment, I really appreciate it.
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Old 05-04-2021, 05:21 PM   #12
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Keep us posted on your findings. Good luck!
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Old 04-24-2021, 02:01 PM   #13
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Puffing out of the oil fill cap is normal. You are missing the gasket though.

I would be concerned if there's any white smoke coming out of the dipstick/oil fill. I'd be interested in seeing compression test results.
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Old 04-24-2021, 08:48 PM   #14
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Tune done? Accessport?
Not knocking you
I fell into same situation bc I was running accessport V1 for 10+ years

I had incredible studder when in 1st gear to start from stopped position
After compression test.....#1 cylinder down to 80
Wasnt internal failures.......just idiot me thinking 12yr old accessport would work on my mods
(Cold air intake/catless DP(did have cat thou))
Ended up with new short block
Machine shop head work (nothing catastrophic)

IMO
That blow off valve/DP might be culprits of your blow by noted in your vid(after a period of time)
Check plugs(mine were ghost white from running lean for so long)
Do compression test

Report back!!
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Old 04-24-2021, 08:53 PM   #15
cproo12
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Quote:
Originally Posted by AliBenn View Post
Tune done? Accessport?
Not knocking you
I fell into same situation bc I was running accessport V1 for 10+ years

I had incredible studder when in 1st gear to start from stopped position
After compression test.....#1 cylinder down to 80
Wasnt internal failures.......just idiot me thinking 12yr old accessport would work on my mods
(Cold air intake/catless DP(did have cat thou))
Ended up with new short block
Machine shop head work (nothing catastrophic)

IMO
That blow off valve/DP might be culprits of your blow by noted in your vid(after a period of time)
Check plugs(mine were ghost white from running lean for so long)
Do compression test

Report back!!
Yep, going to check plugs. Waiting on flex head ratchet to arrive. I don't have an accessport, I also have no idea if the car is tuned for the downpipe or not.

Since it originally had 3 cats and now only has 1, I think a tune should be done, but not sure. Really hoping its not ringlands, thank you so much for the information and suggestions.
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Old 04-24-2021, 09:45 PM   #16
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Subaru does not have crazy pricing for their short blocks
List is $2174
You can get for cheaper thou.....good deal is $1750 that is STI block
10103ac870

Let's see what plugs/compression test shows
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Old 05-04-2021, 09:06 PM   #17
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My 05fxt w broken ringland ran through oil daily. My 06fx that I put counterfeit rings in smoked like a fire but used much less oil than the fxt w 1 bad ringland.
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Old 05-18-2021, 11:34 PM   #18
cproo12
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Welp, I don't think people will still be checking back on this post regularly, so I don't expect anybody to see this, but I will post anyways for those in the future who find my thread in case I eventually solve the problem..

I replaced all the spark plugs with brand new OEM (NGK) ones, and I cleared the code (At some point I started getting a misfire code on cylinder 3). I am disappointed to say that after replacing the spark plugs, I still get a misfire on cylinder 3.

I also switched the coils around. Put cylinder 1 on cylinder 3 vice versa. Still misfire on cylinder 3. Pain.

I bought a new coil in case somehow the misfire code has nothing to do with whatever this problem is, and I'm just not feeling the misfire (could be related to my timing belt, but I'd expect to feel a tooth off worth of timing, especially during advancement under boost [I am intake AVCS equipped] )

If this brand new coil doesn't eliminate it, I am going to get a compression test, contemplate life for a few days, then try to find time to tear the heads apart. Hoping the new coil solves my problems... but not feelin optimistic right now :'(
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Old 05-20-2021, 09:46 PM   #19
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Im checking!!!

Man, I did same thing
I screwed around with fuel/plugs/coil packs for a month
I think I was just denying the fact that I did not want to do compression/leak down tests
(Because I was praying was something else)

Just like others saying
Do the test and Face the Music
(As crappy as the music sounds)
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Old 05-20-2021, 10:29 PM   #20
cproo12
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Quote:
Originally Posted by AliBenn View Post
Im checking!!!

Man, I did same thing
I screwed around with fuel/plugs/coil packs for a month
I think I was just denying the fact that I did not want to do compression/leak down tests
(Because I was praying was something else)

Just like others saying
Do the test and Face the Music
(As crappy as the music sounds)
I'm not avoiding a compression test, I just don't have the tools to do it XD

I need to go buy a kit, but the closest store that sells one (harbor freight) is an hour and a half from my house. I would buy one from amazon, but I have a harbor freight $50 gift card. That's my current situation XD

I will be shocked if the issue here isn't ringlands, but also, I am confused, because like others say, I would expect the issue to go away as the car warms up if it was ringlands. In my case, it gets worse as it's warmer.
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Old 05-21-2021, 10:38 AM   #21
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Is there a parts store like auto zone any closer? They rent them for free.
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Old 05-21-2021, 11:08 AM   #22
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My misfire code is injector related and low load
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Old 05-21-2021, 02:05 PM   #23
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Also could be a bad wire on the #3 coil- if it has corrosion or a crack it could cause some of this. but compression test first. Amazon it! https://www.amazon.com/AZUNO-Compres...xpY2s9dHJ1ZQ==
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Old 06-05-2021, 02:02 AM   #24
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Okay, I am back. Finally did a compression test... and here lies my issue.

1,2,4 easily crank 110-120psi. Not perfect, but acceptable for a near 200k mile engine I think

3 however... 15psi. I thought I had the compression tester on it wrong. Nope, tested three times. Same result.

I had all ignition coils unplugged, fuel pump unplugged, throttle wide open (pedal to the floor, not sure how that translates as I have an electronic throttle)

So, the car drives fine, which honestly shocks me. The only time I would even notice it is the rough idle. It does not burn a crazy amount of oil, there is no smoke coming from the crankcase, I'm seeing normal air fuel numbers on my wideband sensor, so I think it's an issue with the valves/timing.

I did my timing belt myself, and it was my first time doing a DOHC timing belt, but the issue was happening to the same exact extent before I did the change, so I don't think my timing is off.
Maybe I need to adjust valve gap?

I am not sure what my next move should be- inspecting cylinder with camera? Pull motor and inspect heads? I can afford to have somebody else do it, but I really want to DIY this for the learning experience.

Any advice welcome.

Last edited by cproo12; 06-05-2021 at 02:11 AM.
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Old 06-05-2021, 08:03 AM   #25
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Default 06 FXT 5mt - Rough Idle only when warm (Ringlands??)

With a compression test of 15 psi, you should do a leak down test. If you only bought a compression tester and it has an air inlet nipple you can use it for the leak down tester. By now, your not interested in the leak down value just where the air is going. You should be able to tell where the air is going and will probably give you the answer as to where the damage is. Coming out the intake, then intake valve. Coming up the exhaust, then exhaust valve, coming out the crankcase, then ringland.

Last edited by vanman23; 06-05-2021 at 08:09 AM.
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