2006 Pathfinder - Camshaft Pos. Timing CEL - Alternating Banks

[kphoger]

A few months ago, I had the oil pump replaced on my 2006 Pathfinder because of low oil pressure at idle. Several other things ended up getting replaced along the way, including the notorious rear timing cover gasket. The low oil pressure problem is better but not eliminated. Anyway, while they had things taken apart, they noticed that the timing chains and guides needed to be replaced because of the plastic had broken. It was in the shop for several weeks having all of that done, the job having ended up being pretty major work for that size of a mechanic's shop.

After I picked it up, it idled kind of rough, and then it developed valve clatter. The CEL code was for misfire and camshaft position timing over-advanced on one bank. Back to the shop it went, and they replaced the VVT solenoid on that side. After I picked it up, the clatter came back, and the CEL came on for the opposite bank. They determined that they had magnetized one of the cam phasers by setting it on a magnetic shop tray while doing the timing work, so they bought a replacement cam phaser and put everything back together.

A month or two went by with no misfire problems, and then a few weeks ago I noticed a rough idle at red lights on my way home from work, plus what sounded like very faint valve clatter. Ran a CEL code scan, and it came back as camshaft position on the FIRST bank again. I took it to the mechanic, and the owner of shop drove it back and forth to home/work every day in an attempt to replicate the issue, but it didn't happen for him. So I picked it up and they told me to bring it back when it happened again, so they could read the CEL freeze frame data. A few days later, it happened again, and this time the CEL code was for the SECOND bank again. That makes two CEL instances on each bank, in alternating order.

The freeze frame data didn't have anything useful, just fuel economy and stuff. They drove it every day for a week, and it didn't do it for them. So they have nothing to go on, and they have no data to steer them in the right direction. I don't really feel like having them replace random stuff, hoping that something works.

Since then, about two weeks ago, I haven't noticed any rough idle, but I do occasionally hear what sounds like faint valve clatter. A couple of times, it's been louder. But it only lasts for a few seconds, as if the VVT is "fixing" the problem in short order. I also hear a faint ticking when on the gas while the engine is cold, but it goes away after several blocks.

Any ideas?

Additional data:
Odometer = 220,000
Other CEL Codes = Catalyst performance (there since I bought it 3-4 years ago)