P0011 and P0021 Codes

[06-XT-Owner]

I've read a lot of articles and other posts on these two codes, but I still have some questions.

 

It seems that a lot of people say the car throws these codes once the turbo starts dying. But what exactly causes these codes to happen together? My turbo appears quiet and doesn't have any shaft play. I took the AVCS valves apart and they operate freely and operate when voltage is applied, and there was no debris in them. My oil is clean and it's been changed twice since I accomplished a head gasket job on the car a few thousand miles ago. I'm using Rotella T6.

 

From what I understand from reading other posts, I may have an oil flow problem to the AVCS due to dirty screens. I'm 95% sure both screens were removed as when I had the heads off, I'm sure I checked for them. I'll say 95% sure since my brain isn't as young as it once was. It seems to me that if the screens were in there and dirty, only one or the other code would have shown up, but it's weird that I'm getting both codes.

 

I'm considering dropping the oil pan to take a peek in there. My thought is that if my oil screen is dirty/clogged, that would cause low oil pressure and thus a lack of flow at those two valves. But before I do, I figure a quick post may save me some time. I'm not getting any oil pressure lights.

 

Can someone help me understand some background to both of these codes together and what I should be looking at?

 

Tom

[apexi]

One guy said here this happened from the timing belt being two teeth off at the crank

https://legacygt.com/forums/showpost.php?p=4503241&postcount=28

 

I'm also kind of wondering about a cracked oil pickup tube.

https://legacygt.com/forums/showpost.php?p=5886069&postcount=44

 

I think I've read the telltale signs of that are a flickering or solid oil light, but I wonder if it could also cause low flow and trigger those two DTC's. Just somethin to check for I guess if you do decide to drop the oil pan.

[06-XT-Owner]

Thanks for that reply. Both interesting possibilities. I'll have to watch the oil light the next time I start it to see if it lingers. Concerning the timing belt being off by 2 teeth...would the car even idle with it being off 2 teeth? Mine idles smooth and revs good.

[Underdog]

You are on the right track. Both codes simultaneously would suggest low oil pressure at both OCVs, which could be due to dirty banjo screens or low system pressure. The low pressure light is not useful for diagnostics because its basically a "no pressure" light - you'd need a mechanical gauge for troubleshooting (either a permanent one or a tester). You could also just crack loose the banjo bolt on top of each OCV for a very quick check, though make sure you have a rag handy.

 

 

If you're able to datalog you can monitor the OCV duty cycle and VVT advance for each bank, to see if it is only occurring under specific conditions.

[Underdog]

Here is the detecting criteria for P0011 & P0021 from the FSM.

P0011 & P0021 Detecting Criteria.pdf

[xt2005bonbon]

If you're able to datalog you can monitor the OCV duty cycle and VVT advance for each bank, to see if it is only occurring under specific conditions.

 

 

Under normal conditions, both VVT advance angles should be in sync between each other. In general, the value remains zero under no load. Once you begin to apply load (hit the gas pedal), the VVT advance would quickly rise for both devices. They must rise in sync and remain in sync. In my case, under load, the angle can rise up to 10 degrees when the engine is warmed up.

[apexi]

Concerning the timing belt being off by 2 teeth...would the car even idle with it being off 2 teeth? Mine idles smooth and revs good.

 

I didn't reply at first because I don't know the answer, but I don't want to seem rude. Not sure.

[xt2005bonbon]

All I know about the teeth count is that the FSM states that if the timing belt is off by more than 3 teeth, the valves will touch the pistons. If I recall correctly, my timing belt skipped about 4 teeth once and the engine would not start. Huge after fire. LOUD

(skipped due to timing belt guides being improperly installed by whoever owned the car before me). In any case, if you say yours is idling and running fine, then should not be it.

[06-XT-Owner]

Thanks for those replies. I do have a BlueDriver scan tool that I can track live data, but I'm not sure if it will read the OCV duty cycle and VVT. I've never tried to do those.

 

Here is an update. I pulled the engine as I want to check my valve clearances since I didn't know to do that when I replaced the headgaskets. I may be asking more questions concerning that task.

 

I found that my driver's side intake cam was off by 1 tooth. I'm pretty good about making sure the timing marks are dead on and rotating the engine a few times by hand when I replace a timing belt, so that is bothersome. I wonder why it's off. Did it skip or maybe I really was off a tooth and didn't notice, but I'll do better when putting it back together this time. My rear main seal has a very slight leak, so I'll replace that while I'm in there, and I'll reseal the oil separator plate and put a new o-ring on the wrist pin access plate also. Why not do it when the engine is out.

 

My turbo seems to have slightly more side-to-side play than I remember it having, but it still doesn't move in/out. How much side-to-side play is too much? It's not rubbing the housing edges, but it's getting close. I would estimate 1/16" play from pushing it all the way from one side to the other. When pushed towards the edge, it probably has about .004 clearance between the housing and fins. Don't these things have a little play when there's no oil pressure or am I just being hopeful? Lol.

 

All the advice is appreciated. More to follow tomorrow when I pull the valve covers and oil pan.

 

Tom

[06-XT-Owner]

Here's an update. I pulled the oil pan today, and it's clean. No debris, no shavings, all is clean.

 

I also pulled the valve covers off to check my valve clearances, and all of those were good. Two of the intake valves were a little tighter than the rest, but a .007 feeler gauge slipped right in whereas a .008 would not. So I'm guessing all is well there. I think allowable is .0071 to .0087 or something like that.

 

Now for the not-so-good finding. I do have quite a bit of white gunk in my driver's side valve cover. I'm obviously getting some moisture into my oil someplace and it's collecting in the valve cover. Any ideas on this? Since I have 2 vent hoses on each valve cover, is there a way to redirect those into a container of some sort and monitor what's going on there? Can someone help me understand those hoses?

 

I'll try to post a picture below

 

Tom

 

Edited February 13, 2021 by 06-XT-Owner
trying to post a picture

[06-XT-Owner]

Let's see if this picture-link works. If not, sorry. I'm a moron.

 

[apexi]

I'd like to see you get this figured out, but I worry that this section doesn't get a lot of views. I might ask about this in the 2005-2009 legacy forum if I were you

 

https://legacygt.com/forums/forumdisplay.php/fourth-generation-legacy-2005-2009-10.html

[Underdog]

The path from the oil pump to the OCVs is pretty short and direct. Can you supply pressure to the oil system and check for flow at the banjo on top of the OCVs like I suggested? Would rule out clogs without further disassembly of the valve train. Search for my DIY priming tank thread if you don’t already have a way to apply oil pressure on the stand.

[06-XT-Owner]

Underdog....I think my codes were from my driver's side intake cam being a tooth off, therefore the ECU seeing a difference in the two intake gears. That's the best I can guess without being for certain. I'm going to pop those two cam gears off tomorrow and pull that oil line from the front of the head to the OCV and check for clogs.

 

Do you have a link to your DIY priming tank? I think I'm a little more concerned with the condensation in my valve cover at this point. I'm trying to figure out the best way to test for water intrusion into the oil system with the engine out of the car.

 

Tom

[06-XT-Owner]

I'd like to see you get this figured out, but I worry that this section doesn't get a lot of views. I might ask about this in the 2005-2009 legacy forum if I were you

 

https://legacygt.com/forums/forumdisplay.php/fourth-generation-legacy-2005-2009-10.html

 

Thanks. I posted it over there. We'll see if I get any hits.

[Underdog]

https://legacygt.com/forums/showthread.php/diy-oil-system-priming-tank-214760.html

[06-XT-Owner]

Very cool idea. Thanks for that. That's my kind of solution for a problem instead of spending $200 for a specialized tool.

 

Tom

[Underdog]

Just saw the pic of the inside of your valve cover and for sure that gunk could have clogged the OCV banjo/lines or the cam sprockets themselves. It’s even possible that your driver side cam is stuck in a non-zero position, making it appear that the timing is off. Here’s a thread where I was chasing down a similar problem that ended up being a tiny piece of piston stuck in a cam gear: https://legacygt.com/forums/showthread.php/help-request-avcs-related-problem-131462.html?t=131462

[apexi]

For what little it's worth I get the impression this is a common thing on turbo subies in cold environments, I did a bunch of googling around earlier today.

 

This post on nasioc kind of interested me. I wonder how old your pcv valve is?

 

"the buildup might be related to the colder temps we are running into, causing what would usually remain a mist to clog up your breather tubes.

_____________________________________________________________

This is the most logical explanation. When the warm oil air hits the walls of the cold tubing, it turns into the creamy milky substance you speak up. A little build up isnt going to hurt anything but if you have a bunch of it i would start with the pcv like stated above.

 

This exact problem has been a major pain in my butt the last few months because we are in the middle of designing a product that deals with this area. With our prototypes of this product we have found that when we delete the pcv we get a bunch more milky oil/air mixture, but when we resume using the pcv most of the milky substance goes away. Again, this only happens in cold temps(say less than 45 degrees). I'm assuming it is this cold in PA right now.

 

Justin

GrimmSpeed"

https://forums.nasioc.com/forums/showpost.php?p=29041261&postcount=13

[06-XT-Owner]

Thanks for that apexi. It's very cold up here right now, and my daughter was driving this car, and only making very short trips (less than 3 miles) to work and home. I may route my PCV hoses to a jar and see what happens. At least until the weather warms up, but I'm also going to try to pressure test the coolant system while the engine is out of the car. I'm blocking off the upper and lower radiator hose connections along with the heater core connections. I'll fill it with water and apply some pressure to the system and see if it holds. If it doesn't, I'll start tracking down the leak. If it holds, then I'll have to assume that your theory is correct and hopefully, my catch jar will allow me to catch the white crap. I'll then drive it until summer and then pull the valve cover off again and see if the white stuff has returned.

 

Any ideas on how to check the cam gear to see if it's returning to it's home position?

[06-XT-Owner]

Underdog,

 

Both of the banjo bolt filters were still there, and both were dirty, although not so bad that it would prevent oil flow. The oil lines between the banjo bolts are clean. The white gunk appears contained in the larger PCV hose and that one valve cover. The OCV valves are clean. I read your article about taking apart the intake cam gear, but I don't think I'm ready to dive that deep into it.....that last question about the cam gear was directed to your expertise. How can one tell if it's stuck in the open position?

 

Tom

[Underdog]

Sounds like the white gunk could very well be the normal stuff that builds up as others have mentioned, though I’ve never seen quite that much inside the valve covers before.

 

As far as the cam sprocket - I don’t think there is a quick visual indicator of its phase. I was not thinking correctly when I suggested that as a cause for your timing being one tooth off; the sprocket would still be in time with the rest of the valvetrain. Since your lines are clear it seems unlikely that the sprockets are both jammed up, but short of disassembling them or monitoring the VVT advance when the car is running I can’t think of an easy way to inspect the phase.

 

Unfortunately it’s harder to diagnose since we don’t know if the problem is one side (with the other being cause by the timing being off by a tooth) or something affecting both sides. But if you look at the detecting criteria and the hydraulic circuit that makes up the AVCS, it’s pretty clear that it’s either low pressure, a blocked passage, or jammed up sprocket. Anything related to the electrical control side would have its own code.

[06-XT-Owner]

Given that my filters were dirty, I'm beginning to think it could have been an oil flow problem, or just the one cam being a tooth off that caused those codes. The more likely cause is the tooth off, as when the VVT advanced, the computer saw two different readings from the cam sensors and since it didn't know which was correct, it could have thrown both codes. That just a theory, but now that I've removed the banjo filters and am in the process of adjusting the valves with different buckets, I'll put the engine back together and see what happens. I'm going to pressure test the coolant system with then engine out and see if I have any leaks. If it holds pressure, then I'll assume the cold weather is the cause of the white gunk and I'll run my PCV hoses through a jar to see what's happening there.