2015 2.5 CX-5 knocking with p0015&17

New member here. Thanks for reading!
A little background: I just picked up a nice (looking) 2015 cx-5 with just over 100k miles, and the 2.5 engine. I acquired it from a tow company with a clean title for $6500, but it knocks and has a P0015 and P0017 code.
I searched high and low online and haven't found another instance of these codes with a consistent loud top-end knock.
I located a replacement engine before i bought it, just in case they ran it out of oil, or it's cost prohibitive to repair the engine.
I am an accomplished hobby mechanic, but I'm busy, and so my master mechanic brother in law is doing the repairs. He's only taken a brief glance at it with his stethoscope, but he agreed it's in the top end. And, the codes are pointing us to maybe a slipped timing chain or? He has seen cams knock like this, and I've heard loose lifters slap similarly.
Anyhow, any advice is greatly appreciated on what it might be, and if I'm going to spend too much in labor messing with it, and should just swap the engine ($1000-$1500 labor).
I am afraid they ran it out of oil or raced the engine a lot, and that it may be crank bearings next, but I don't know what to expect out of these engines.
I was thinking that an oil analysis would tell me if there was massive abuse or oil starvation via bearing material?
The knock is persistent through out the rpm range, and it's pretty loud, but not a rod. It has low power, but I'm guessing it's in limp mode.
The oil needs changed, and is brown, and smells a bit like fuel, but probably just has 5k miles on it and is pretty normal. No silver in the oil on the dipstick.

The previous owner up and moved to Holland and abandoned the car. So, who knows if they decided to race the heck out of it before they left. Looking like they came into a big inheritance or sugar mama/daddy, who knows...

Lastly. Can the cam timing control apparatus fail in such a manner as to have a valve contact a piston? That might be what we're hearing with the knock.

Thank you for any expertise on this problem. I am determined to get it back on the road and put many miles on it!
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'17 CX-5 Select
The exhaust VVTI phaser on passenger side of engine, if oil starved, leaking pressure badly, or the oil control valve was defective and not pressurizing the phaser correctly, can make a heck of a knock. And it would be consistent with P0015
Many thanks, I read up on that vvti phaser and it sound like it destroys other parts as well? I can get a used engine with 100k for $700, but then there's the huge labor bill to swap it. but you know how used engines go... not sure what to do on this yet. Looking for info on diagnosing the vvti phaser.
I'm thinking it's pretty risky to even start this thing now? Some diagnostics might require the engine running, and a hot oil sample might be better for an accurate oil analysis.
What would you all do?
My brother in law is afraid that just tearing into it may not reveal the problem. He left on vacation the day I got it to his shop😑


'17 CX-5 Select
A VVTI/phaser failure won't allow valve contact with pistons--that I can conceive-- but sure can make it run crappy and of course make a racket.

If you are not getting misfire codes and misfire counters (if you have the ability to read them) are OK, and the noise is from the head, then from what you shared, the engine may be sound overall and just need VVTi work, or a used head. No idea on cost, as I haven't had to do that type of work on my Mazda.

If it were mine, I'd pull the valve cover, clean out the oil control valve with carb cleaner, bench test the oil valve for free movement, remove the VVTi phaser to inspect, and clean that as well. Essentially free, other than time. Having the valve cover off will also permit close inspection of the valve train, evidence of shellac, sludge, lobe damage, etc.
Sounds like a good plan, thanks again! Hopefully we can tell if the timing chain is loose with only the valve cover off?
Oh, and can you tell if the phaser is bad by looking at it?
I forgot to mention that the tow truck guy said the car ran through the gears well, as he actually drove it home. Just in limp mode I assume. I'm not going to start it again until it's fixed, for fear of more damage


'17 CX-5 Select
I've never had one of these apart, but from teardown videos, you can see the chain and should be able to feel the tension with the valve cover removed. Pretty sure you'll have to remove the phaser to inspect internals.
Sounds good. He pulled the codes with a higher end tool, so pretty sure it only had those 2 fault codes

I've found where there's a couple of instances of timing chain issues, but it looks rare. And, it looked like the phasers are really reliable in the 2nd gens, but the 1st gens had lawsuits over failures?

These must not fail much or there would be more commentary I assume. I'll take that as a good sign😀
Thank you AVC for pointing me in a good direction!