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Old 03-30-2012, 12:49 PM   #1 (permalink)
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Lightbulb p0021 That Itch You Can't Scratch

Hello all! I have studied (not just read) close to every subaru and non-subaru related p0021 thread. It seems that for most of these threads there are alot of possible solutions, but rarely is there conclusive ending to what really can fix this infamous code.

So here begins the tale of my FXT and her p0021.

I own a 2004 forester xt. I purchased the car with 88,000k completely bone stock with receipts for every synthetic oil change. All was well and the car reached 100,000k so I excitedly purchased my timing belt kit from Subaru. This kit included a new:
Water Pump
Thermostat
Gaskets
Timing Belt
Timing Belt Tensioner
Idlers
Coolant (Not from Subaru)

Now for the timing belt install, I asked my father who was a master tech at Mercedes Benz for 30 years to help me. Mind you, he didn't actually help me...instead he completely stole my thunder and did the whole thing himself and I got to pour the coolant after it was all done. This is not a complaint at all since there were zero issues, nothing broke, it was free, and it only took him a Saturday morning to finish the whole job.
Fast forward about 15,000k. I am driving home from work and the code pops on. P0021. I drive it to the rents house and my father reads it and we are baffled. The timing is obviously on (if it wasn't the car would run like a diesel) and there is no power loss. We decide to leave the car and research a little, which brings us to...

THINGS I HAVE DONE TO TRY AND FIX THE CODE P0021:
Drained, and refilled the oil more times than I can count
Run Seafoam in the oil
Removed all banjo filter screens from oil lines
Removed, cleaned, and swapped AVCS Solenoids
Replaced Crank sensor
Replaced Cam sensor
Replaced driver's side intake Cam Gear
Checked wiring from the ECU to the solenoid

Nothing has fixed the code. The car runs like a top and never stalls and the car now has 138,000k. I get the same gas mileage as when I first purchased the car. I just recently purchased new heads that I plan on beefing up slightly and tinkering with just in case I have to pull the heads off of my car to resolve this issue. As for the engine mods done to my car:
Accessport installed after the code came up
Intake
Full exhaust (catless)
Denso Platinum spark plugs (changed about 5,000k ago)

The car only sees synthetic oil. I have used Rotella 5w-40, Motul 5w-30, Amsoil 5w-30, Valvoline 10w-30, Mobil 1 0w-40 (only once) and now Castrol 0w-30. Mainly I have stuck to Rotella and Amsoil. I change the oil every 3,000k and sometimes sooner and I don't burn oil.

The reason I am writing this extensive post is to gather as much information on this code as possible and to hear all of your experiences. I have seen the issue be something as small as a oil supply screen, all the way up to starved turbo. My car falls somewhere in the middle of that and I'm sure lots of other subies do as well. If anyone has any questions or comments please feel free to post!

Thank you everyone!
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Old 03-30-2012, 01:35 PM   #2 (permalink)
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Default P0021 - "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 2)

Is it possible the timing could be off 1 tooth causing that?

Causes

A P0021 DTC trouble code may be caused by one or more of the following:

Incorrect camshaft timing
Wiring problems (harness/wiring) in intake timing control valve control solenoid system
Continuous oil flow to VCT piston chamber
Failed timing valve control solenoid (stuck open)
http://www.obd-codes.com/p0021
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Old 03-30-2012, 06:53 PM   #3 (permalink)
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I thought this as well. I checked the timing when the code first appeared, and it was spot on. The timing had to of course be redone after installing the cam gear and its still where it should be. I've gotten pretty good at pulling the timing covers off
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Old 03-31-2012, 09:37 AM   #4 (permalink)
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any more suggestions?
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Old 03-31-2012, 10:16 AM   #5 (permalink)
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man, wish I had more ideas for you, you've tried it all!
But here's my only input, probably not helpuf, it's just what comes into my mind as even possibly relevant:

The only *slight* difference in what I did to get my P0021 to go away was a shade tree oil flush using a very high detergent oil (ATF) to help remove contaminants. I drained oil, added cheap dino & 1 quart of ATF and drove it around for 5-10 minutes. Then I drained the oil again and applied compressed air to my oil system with first the drain plug open and then the oil filter off to "flush" it. Taking it to an oil change shop that has an actual oil flushing machine would be better. Have 'em flush it then just put in whatever Dino oil they have, go home and drain that and add back in your syn of choice(just to save a few bucks and get one more contaminant drain in there).

The way I understand this issue is it is happening due to not enough oil pressure to operate the OCV on the passenger side. (hence why the driver side is "overadvancing" in relation to the passenger side that is not advacning at all) I believe this OCV is the last component to get oil before it's returned to the pan so any flow blockage anywhere in the system will result in a permanent pressure loss that manifests itself in not enough prssure to operate that last oil fed component, the passenger side OCV.
My issue occured shortly after a turbo failure so I think there was some residual bearing material getting fed to the passenger side OCV since it's right after the turbo so it just needed to be flushed out. It seems you're right around the mileage where the stock turbos seem to let go it could be sending a little bearing material through passage ways leading to the OCV and therefore creating a pressure drop.

Oh yeah, have you tried watchin the ACVS while driving? Once up to temp both sides should be advacning between 1 and 15 or so. Before my flush the passenger side would only register a 1 for advance after you revved it and it almost died, the 1 would pop up around 600 rpm has it would "catch" itself. This data could give some insight on the OCV operation??

Good luck man, I can empathize
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Old 03-31-2012, 07:35 PM   #6 (permalink)
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Thanks for the info! I have datalogged the OCV and it shows the right OCV at 0, while the left being at 32. While I have run seafoam to help clean the system, I've yet to run any ATF to help act as a detergent. I plan to definitely swap some dino oil in with ATF and then flush the system to see if I can discover any gunk.
As for the turbo going, I sure hope this isn't the case! The code came on quite some time ago and I've shown no signs of turbo failure, no burning oil, no boost issues. (that I know of) It makes sense that there is probably a blocked or at least restricted flow of oil somewhere is the system. I've done alot of research on this code and I've kept in mind there could be an oil flow situation, but I've always been wary of "flushing" my system.

I appreciate your input, it's definitely motivated me to clean the oil passages out and see if anything turns up.

Thank you again! Feel free to keep posting
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Old 03-31-2012, 08:33 PM   #7 (permalink)
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I totally jinxed myself. Not 30 minutes after my last post I popped the P0021 code... Argh. So please feel free to completely ignore everything I wrote!
So it lasted about 1900 miles with the last flush, guess I'm going to try another flush and see what happens...
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Old 04-01-2012, 01:39 PM   #8 (permalink)
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Wow! I just did a flush today and I've only driven about 8 miles so I won't know for a little bit if the code has come back. That's really unfortunate that the code reappeared...
I'm starting to think it might be time to replace the old hard oil lines with some soft oversized lines to help with oil flow.
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Old 04-01-2012, 07:51 PM   #9 (permalink)
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Apprently my car wants a 2000 mile oil change interval...?
Relapse summary:
About 1 week ago I mentally noted that my oil, which had been looking beautiful up until that point, had almost overnight started to look much darker then the P0021 popped up again yesterday. This was just under 2000 miles since my last oil change/flush (it fixed my P0021). Yesterday, after a few short trips, the CEL turned it self off. It came back on again during the next drive. I reset and it came on again today. I decided to buy some cheap oil and try the last thing that worked.

So, I just got done doing a drain and fill with some havoline dino (on sale) just to see if a simple oil change could fix it. After about 5-10 minutes of driving it was still exhibiting the same symptoms, 0 ACVS on the left side while the right was bouncing around 10. I was bummed. After a quick stop, I was headed home and got on it one last time and the left side ACVS jumped up to 10 and started bouncing around. Weird, but driving around for another 10 minutes and the right and left stayed in harmony. I have a suspicion that my turbo is starting to go so I'm hoping that is at the root of all this (contaminating my oil). I get my freshly rebuilt 18G back from FP tommorrow so I'll do another shade tree flush before putting in the new snail and switch back to some higher quality syn oil.

Hope your still P0021 free and holding!
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Old 04-02-2012, 09:53 AM   #10 (permalink)
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Sounds all too familiar! My code came back of course when I drove it last night While the engine flush was fun, it definitely didn't loosen up any gunk and the oil came out just as fresh as when I put it in.
My guess is whatevers causing the blockage in the oil flow, isn't something small or else higher oil pressure and a flush would have probably kicked it out of the way. It has to be something that is the same size as the tiny oil passages.
I'm still learning, and I've never done a turbo upgrade, but I'm pretty sure when you get a larger turbo they supply you with larger feed lines and banjo bolts as to not starve the turbo. Logically then wouldn't I be able to swap out the hard oil lines on the head to braided lines with larger banjo bolts? After looking at the oil lines today,(and maybe it's just me) the ID looks...well...piss poor at best.

I took a picture of the heads with the oil lines on just for reference. Also, this is not the head off of my car These are the oem heads that I bought that still need to be machined so that I can start pouring money into them.



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Old 04-02-2012, 11:42 AM   #11 (permalink)
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I was battling this code after my first motor build, turns out my heads were all messed up, not shimmed correctly etc... but your car is stock so that wouldn't be the problem.

My mechanic however was battling this code on a different car and discovered that the head gaskets played a big role in throwing this code. Again, your motor is stock so this obviously shouldn't apply to you (Unless head gaskets were done before you bought the car), but heads that were decked too aggressively or too many times, although still withing spec, caused this code for whatever reason. They found going to an .045 head gasket helped eliminate the issue.
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Old 04-02-2012, 01:00 PM   #12 (permalink)
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Default cam sprocket question

When you replaced your cam sprocket did you use the subaru tool to hold the cam in place and or the tool that fits into the cam to allow you to hold it well you loosen the bolt on the cam sprocket or did you make your own tool?
I have a very small oil leak on one of the cam seals I want to repair when I do my timing belt.
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Old 04-02-2012, 06:30 PM   #13 (permalink)
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Quote:
Originally Posted by montanasuby View Post
When you replaced your cam sprocket did you use the subaru tool to hold the cam in place and or the tool that fits into the cam to allow you to hold it well you loosen the bolt on the cam sprocket or did you make your own tool?
I have a very small oil leak on one of the cam seals I want to repair when I do my timing belt.
I'm pretty sure we used something similar to those oil filter wrench chains. Then we used a longer breaker bar and it came loose without too much effort.
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Old 04-03-2012, 04:02 AM   #14 (permalink)
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Seems like you've tried everything. I don't know if you have a clogged screen, but Subaru does have a flush.

http://www.scoobymods.com/showthread...ine-13825.html

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Old 04-03-2012, 03:31 PM   #15 (permalink)
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Quote:
Originally Posted by bluesubie View Post
Seems like you've tried everything. I don't know if you have a clogged screen, but Subaru does have a flush.

http://www.scoobymods.com/showthread...ine-13825.html

-Dennis
Already removed the screens and did an engine flush
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