P0016 on a 60k mile car

[rusty959]

Originally Posted by Ultramaroon

Rusty, what did you do with the sprockets you removed?

Nothing other than take them out. I bought a new intake sprocket, came in yesterday, but I'm now out of town until Friday. Since I have a new one I'll probably further take my old one apart and see if there is anything else of note wrong with it. I expect I'll have it back together in about 2 weeks, at which point I'm 98% sure the code will come back, at which time I'll decide if I want to get a new ECU or try disabling the code.

[TheStig85]

Originally Posted by rusty959

To see if your timing is off you would have to remove the cover, but if that happened your sprockets would have been incredibly damaged or some freak case that I can't imagine. Probably not the issue.

I drained my oil before pulling the cover, and once I did that I didn't have very much drain. Throw a pan or some kitty litter below and call it good.

No idea on the shim, if it were me I'd probably make my own.

You already swapped ECU's? Any chance you swapped in a broken one?

I wouldn't count completely out the chance of sprocket being damaged just because it drives fine. If it really is this spring plate thing I can image it being broken just enough that the ecu can correct enough to make it not noticeable for the most part.

It was a brand new ECU from Subaru. Even made sure it was the updated part No.

My only guess is changing the oil (it's due) and the shims on the sensor. I'm at a loss otherwise.

[rusty959]

Originally Posted by TheStig85

It was a brand new ECU from Subaru. Even made sure it was the updated part No.

My only guess is changing the oil (it's due) and the shims on the sensor. I'm at a loss otherwise.

Your sprocket hasn't been out, correct? could still be a damaged sprocket.

[TheStig85]

Originally Posted by rusty959

Your sprocket hasn't been out, correct? could still be a damaged sprocket.

Not yet, but the car is running smooth. If the timing skipped or a damaged sprocket, I'd imagine the car would be running very rough.

[rusty959]

Originally Posted by TheStig85

Not yet, but the car is running smooth. If the timing skipped or a damaged sprocket, I'd imagine the car would be running very rough.

Lets make sure we are imaging the same thing when we say "damaged sprocket". The damage that typically happens to them is a little plate on the back that limits oil flowing out of the sprocket pops off, shown in some of the pictures of mine. This means the car has a harder, but not completely impossible time controlling the VVT.

My car in stock form also ran fine. I noticed some issues around idle with my turbo tune, but they came and went, sometimes it would be fine for weeks. If it weren't for the CEL popping up I likely would have never faulted anything on the car once I went back to stock.

[TheStig85]

Originally Posted by rusty959

Lets make sure we are imaging the same thing when we say "damaged sprocket". The damage that typically happens to them is a little plate on the back that limits oil flowing out of the sprocket pops off, shown in some of the pictures of mine. This means the car has a harder, but not completely impossible time controlling the VVT.

My car in stock form also ran fine. I noticed some issues around idle with my turbo tune, but they came and went, sometimes it would be fine for weeks. If it weren't for the CEL popping up I likely would have never faulted anything on the car once I went back to stock.

I saw the photos. Is that something that's visible without removing the valve cover though? I have one of those snake cameras that I could use if needed to inspect it. Edit: After looking at the photos more closely... I'm doubting it. Probably have to pull it.

CEL or not, my car has run smooth for as long as I've remembered.

[Ultramaroon]

Originally Posted by rusty959

Nothing other than take them out. I bought a new intake sprocket, came in yesterday, but I'm now out of town until Friday. Since I have a new one I'll probably further take my old one apart and see if there is anything else of note wrong with it. I expect I'll have it back together in about 2 weeks, at which point I'm 98% sure the code will come back, at which time I'll decide if I want to get a new ECU or try disabling the code.

I've seen some hydraulic diagrams and I've been itching to dig into an actual sprocket. Now that you've pointed out the lack of a check valve in the exhaust sprocket, I'm even more curious to see how they compare.

[rusty959]

Originally Posted by TheStig85

I saw the photos. Is that something that's visible without removing the valve cover though? I have one of those snake cameras that I could use if needed to inspect it. Edit: After looking at the photos more closely... I'm doubting it. Probably have to pull it.

CEL or not, my car has run smooth for as long as I've remembered.

Not only do you have to pull the timing cover, you have to remove the timing chain and the 3 torx bolts and pull the sprocket off. The plate sits against the end of the cam.

Originally Posted by Ultramaroon

I've seen some hydraulic diagrams and I've been itching to dig into an actual sprocket. Now that you've pointed out the lack of a check valve in the exhaust sprocket, I'm even more curious to see how they compare.

Mind to share the diagrams? I'll probably take apart the intake vvt but unless I'm 100% I won't mess it up I won't be taking apart the exhaust. Regardless I can document the intake if you are interested in seeing inside.

[Ultramaroon]

Originally Posted by rusty959

Mind to share the diagrams? I'll probably take apart the intake vvt but unless I'm 100% I won't mess it up I won't be taking apart the exhaust. Regardless I can document the intake if you are interested in seeing inside.

Sure! Here's where @mad_sb posted it.

I'd love to see pics if you get around to it.

[rusty959]

If anyone is lazy like me, I compiled the o ring's and oil seal part numbers that should be replaced while the timing cover is off. Sometimes I don't replace things like this because they shouldn't leak but I really don't want to have to pull the cover back off if they do. I'm not going to worry about the ocv ones because it will be obvious if they leak and easy to replace if they do. (and I'm lazy)

806912190 x3 o ring $1.26 https://parts.subaru.com/p/Subaru_20...806912190.html
806924120 x1 o ring $1.88 https://parts.subaru.com/p/Subaru_20...806924120.html
806750080 x1 timing cover oil seal $14.57 https://parts.subaru.com/p/Subaru_20...806750080.html

Not confirmed:
806916080 x1 https://parts.subaru.com/p/Subaru_20...806916080.html o ring for driver's timing chain tensioner. Passenger side doesn't use one. Looks like there is a different part number if you have a super early '12 build date.

[Jamestl]

Well... the nice little code came back today while I was driving for an ice driving event. I just kept on resetting the damn code throughout the day, but otherwise no perceptible with the engine running. Seems like others are having no better luck. Part of me is wondering if this is related to weather?

Anyway I will swap a few more parts and maybe the ECU before springing for a a cam sprocket. Freakin job is like 10% of the cars value... :/

Originally Posted by SLVRSRFR

You are one of the few lucky ones where it may have ACTUALLY just been a bad sensor.

Count your blessings!! lol

[Ultramaroon]

Originally Posted by Jamestl

Anyway I will swap a few more parts and maybe the ECU before springing for a a cam sprocket. Freakin job is like 10% of the cars value... :/

I think that the jammed or leaking sprocket is what causes the ECU to fail by permanently setting some learned trim table to a maximum value which cannot be reset.

That's how I understand the reasoning behind the need to replace the ECU. It is the second part of a cascade failure. It makes enough sense to me that I would consider replacing the ECU only if the issue is not resolved by first replacing the sprocket.

[Jamestl]

The thing that pisses me off is that you don’t actually know whether sprocket has failed. If I just reset the ECU everything worked as before - I noticed zero change. I’m almost tempted to get a new ECU before I change the sprocket given the cost differential. Sigh...

Originally Posted by Ultramaroon

I think that the jammed or leaking sprocket is what causes the ECU to fail by permanently setting some learned trim table to a maximum value which cannot be reset.

That's how I understand the reasoning behind the need to replace the ECU. It is the second part of a cascade failure. It makes enough sense to me that I would consider replacing the ECU only if the issue is not resolved by first replacing the sprocket.

[ApexEight]

Originally Posted by Jamestl

The thing that pisses me off is that you don’t actually know whether sprocket has failed. If I just reset the ECU everything worked as before - I noticed zero change. I’m almost tempted to get a new ECU before I change the sprocket given the cost differential. Sigh...

That's exactly what I did and the ECU swap alone got rid of my CEL. It's been about 3 weeks now.