P0016 on a 60k mile car

[Ultramaroon]

Originally Posted by rusty959

If you don't mind me taking it apart myself first I'll send you mine. Finally home now so I'll be putting things back together in the next week or so.

Sure, that'd be great. I'm looking first to see if, and where the damn thing gets contaminated so, if you find any crap on the first pass, I'd love to see pics.

Let me know about shipping.

[TheStig85]

Do other Subaru motors share the same Sprocket? I see one that's cheap but for a XV Crosstek and Impreza. Would that work? Part number is the same.

[Ultramaroon]

Originally Posted by TheStig85

Do other Subaru motors share the same Sprocket? I see one that's cheap but for a XV Crosstek and Impreza. Would that work? Part number is the same.

Ooo, how much? Assigning the same number to non-interchangeable items is a universal no-no.

If the item is classified as a Field Replaceable Unit, it may look slightly different but must match in form, fit, and function for all higher-level assemblies that are within their defined production lifecycle.

[TheStig85]

Originally Posted by Ultramaroon

Ooo, how much? Assigning the same number to non-interchangeable items is a universal no-no.

If the item is classified as a Field Replaceable Unit, it may look slightly different but must match in form, fit, and function for all higher-level assemblies that are within their defined production lifecycle.

$59.99 Free Shipping

eBay link: https://www.ebay.com/itm/152856333394

I figured why not and ordered one. I don't know if that's the actual cause of my CEL but if I'm going to tear everything apart, I might as well replace it while I'm at it.

[Ultramaroon]

Originally Posted by TheStig85

$59.99 Free Shipping

eBay link: https://www.ebay.com/itm/152856333394

I figured why not and ordered one. I don't know if that's the actual cause of my CEL but if I'm going to tear everything apart, I might as well replace it while I'm at it.

Wow, considering its function, that's dirt cheap.

Beware of grey market sloppy seconds.

[TheStig85]

Originally Posted by Ultramaroon

Wow, considering its function, that's dirt cheap.

Beware of grey market sloppy seconds.

Yeah, that was my thoughts too. I'll inspect it when I receive it, but on a good note, the seller has a lot of positive reviews.

[rusty959]

So I've taken apart my old "broken" sprocket a bit which I'll post about in a bit, but I also took my driver's intake sprocket off to check it. This is what I found:


As you can see, it is not pressed down, and is flush with the cam mounting flange instead of 0.58mm down where it should be. This is exactly how my passenger's one looked when I took it out. As with the passenger's, it was not in securely and with slight touching came the rest of the way out.

So here's the thing. I never threw P0018, but it shows the same physical issues that P0016 showed, assuming that's actually the problem. So I might as well replace it while I have it out, it's just a bit concerning on if this is really the problem or not. I don't think I've seen someone have the opposite bank code pop up once they had the first fixed, so I wonder if I'm an outlier or if this isn't actually the issue. Regardless, if I replace them and the codes don't pop up, I suppose I'll be happy.

We might consider putting together more data on the setups people were running when these issues happened. Personally the two major factors I think could cause an issue were the turbo kit and I ran redline 5-30 with the kit. Additionally I drove it in winter in Indiana quite a bit.

[rusty959]

As promised, here are some findings from taking apart my RH intake VVT.

As mentioned in my last post, this is the measurement of how far down the plate is on my new sprocket. So, if this plate pops, it will move out 0.59 mm. That's all that can happen, it can't move further because it just hits against the cam flange.


New vs old:


This is what lives down in the hole. As you can see it seems like that plunger spends some time touching the plate based on the wear.

Down inside the hole. The center slightly higher hole is blocked with a freeze plug/ball, I assume used to create the hole in the next picture opposite from it.


Next few are various states of dissasembly. I don't think there is anything useful here, but including it in case someone wants to see more.


That thin sheet of metal lifts off, didn't have a close up of it but can get one if someone wants it. The plunger in the top right of this following pic is one of note.




These are where the holes in hole go. Keep in mind they go to 2 different chambers.


So I haven't had a lot of time to process what I've seen, but from a quick comparison to that hydraulic diagram, this the "faulty" plate is part of the detent valve. I'm guessing what is happening is that 0.58mm change is just enough to either block or open up those holes when they shouldn't be which is what causes a slow response, causing the CEL. I aim to do some more measurements and see if that 0.58 looks like it should actually make a difference I just didn't get a chance to do it yet.

I found no dirt, grime, or other contaminants during disassembly. Everything that looked like it should move moved freely. Plunger moved smoothly and all.

[Ultramaroon]

@rusty959, I just spent a couple hours going over the diagrams and your photos. Didn't see your conclusion until just now. I'm thinking the same thing.

Nice photos, BTW.

[rusty959]

Well, now I'm a bit more confused. I figured since the holes are perpendicular to the valve the best way to see what difference that plate makes is by just lining it up in the correct location. Even though the middle of the 3 holes is plugged, it lines up with the inside hole which is not.

This is the max travel position of the plate in the correct position:


This is the max travel position of the plate once it is broken free and is pressed against the cam flange:


As you can see, nothing is really changed.
There are only 2 other explanations that I can come up with. The first is that the spring pressure is slightly different with the plate moved, but based on where the spring is positioned it should be negligible difference.
The other is that oil is meant to flow around the plate, and the flow is limited when the plate is against the cam. There are no openings that go to the top of this valve, but oil definitely flows there because there is a channel on the cam meant to drain from the top. I assume it is just "blowby" oil, but it's there regardless.

At the end of the day, I don't think it matters much in my case. I'm just going to replace both sprockets and hope the problem goes away. The main concern I have is that the sprockets I put in don't do the same thing over time. Since both of my sprockets showed the same symptoms but only one threw a code, I also wonder if most engines have had this problem but only certain situations trip the CEL, at which point it's burned into the ECU and then the ECU needs replaced. Maybe the fact that I was using slightly thicker oil at the end of it's life was enough to trigger it, which makes even more sense if the issue is that plate blocking flow.

[TheStig85]

What exactly is this "burn" in the ECU thing I've heard about before? I replaced my ECU about a year ago with the most recent part number, thinking it'd resolve the issue. Just wondering if I can suffer from this or not.

[rusty959]

Originally Posted by TheStig85

What exactly is this "burn" in the ECU thing I've heard about before? I replaced my ECU about a year ago with the most recent part number, thinking it'd resolve the issue. Just wondering if I can suffer from this or not.

In every case I've heard about, the code keeps coming back even after the "broken" cam sprocket causing the code is replaced. Even a flash wont get rid of it once it is there. Once the ECU gets replaced, the code doesn't come back. Something about learned values or something that can't get fixed. Overall it makes no sense to me (and I'm a embedded software developer) but I'm sure there is a reason somewhere, even if it's a dumb one.

So you got P0016/P0018 and just replaced the ECU without replacing the sprocket and haven't had it come back?

[TheStig85]

Originally Posted by rusty959

In every case I've heard about, the code keeps coming back even after the "broken" cam sprocket causing the code is replaced. Even a flash wont get rid of it once it is there. Once the ECU gets replaced, the code doesn't come back. Something about learned values or something that can't get fixed. Overall it makes no sense to me (and I'm a embedded software developer) but I'm sure there is a reason somewhere, even if it's a dumb one.

So you got P0016/P0018 and just replaced the ECU without replacing the sprocket and haven't had it come back?

I got the P0016 code a year ago. Replaced the Sensor and OCV and it went away. Don't ask me why, but I replaced the ECU too for good measure.

About 9-10 months go by and the code returned. I haven't done anything else aside from swapping OCV and sensors around. Nada... I figured I'll crack her open and replace the Sprocket while I'm in there. No idea if that's the problem or not, but I'm hoping it fixes it.

I haven't attempted shimming the sensor though. Not 100% sure how to go about that.

[TheStig85]

This is the part I got off eBay for $60. Does it look correct from what you guys have pulled out of your cars?

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