weather is looking bad for today so I'll open it up tomorrow and rotate the cam to check. It was mentioned that the gear can be changed without opening the timing cover, is there a secret to this? Do I lift the cam bearings? There's very little room between the intake gear bolt and the timing cover.

I did mine during the initial diagnosis without removing the timing cover by following the shop manual procedure, links are below. I did have to unbolt the cam bearing caps and lift the cam in order to remove the VVT actuator/sprocket and install the new one. Good opportunity to inspect the VVT oil passages in the camshaft are clear...carefully so as not to nick the bearing surface. I used a can of compressed air and plastic straw, gunk came out.

NOTE: I did not remove the exhaust cam, and I don't recall removing the exhaust sprocket but I may have needed to in order to get the side chain off and free up the intake cam lift height. Tie off the main chain to prevent it from falling into the timing cover...I used a large zip tie to secure it to the engine somewhere.

Removal:

http://www.customtacos.com/tech.old/...6ta/007004.pdf

And here is the installation section:

http://www.customtacos.com/tech.old/...6ta/007005.pdf

If you're curious about the internals of the intake cam VVT actuator/sprocket, here are pics of the one I swapped out on mine. My engine was much sludgier than yours due to original owner neglect, but this one was working correctly despite the sludge buildup outside the vane path. Note the big lock pin on the vane hub, and the corresponding hole in the housing...there's a small oil passage at the base of the hole where the OCV sends pressurized oil to unlock the pin.

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Hey thanks for all the info Waypoint, I never would have found these shop manuals.

NOW, this is the part where I lose my mind:

I took the cam bearings out along with the B1 timing and exhaust gears, put air through the oil slots and no gunk came out, just nice pretty oil. The lock pin seemed to function fine so I decided to reassemble the cam and check B2, then I dropped the No. 1 tensioner pin down the timing cover and had to rip it all apart. A 3rd time.

When I inspected the timing marks they are all now PERFECTLY LINED UP. Rotated the crank twice and it's still good. I hate it when I fix something by accident. I have no idea why it's good now but I really would like to know. If this isn't a sign of another problem I'm sealing it up and calling it a day.

EDIT: Nevermind, I rotated it a few times and it's off again.

I decide to measure everything from the kit that I installed, the chain is ok. But there's a difference in the idler and crankshaft sprocket diameters. Idler is 2.5 in. crank is 2.4, the manual says a minimum spec of 2.4 in. but no max. Are they supposed to be the same? Also the chain snugs around the Crank better than the idler. Change in circumference is 1/3 in. which is about how far I'm off the timing marks so...

Could the slightly larger idler be the source of the extra slack in the primary chain?

The extra diameter of the idler gear would decrease slack in the chain, not add more. Visualize the radius of the gear, as the distance from the idler gear bolt downward. A larger radius (1/2 diameter) would move the chain downward, away from the intake camshaft sprockets...lengthening the travel path of the chain and reducing slack.

Here's my thought: you verified that the lock pin was locked. This pin locks the intake cam in maximum retarded position until pressurized oil unlocks it and fills the VVT chamber, causing the vane (which is bolted to the cam) to advance the cam.

We know that a stretched chain causes P0016 consistently. There's no evidence I found of a P0012 from chain stretch.

We know from the shop manual that P0012 is a dynamic test by the ECM as the OCVs are actuated, and results when the cam does not advance to the expected position relative to crank position.

So...I'm thinking the actuator pin may not be unlocking. Again, the engine had this error code before all the new timing components were installed. I'd install a new Toyota VVT actuator/sprocket assembly at this point.

As far as your visible timing retard at the intake cams, what brand was your timing kit? Possible that this was a chinese knockoff and the crank sprocket and/or main chain are not to spec.

I have the factory idler gear from mine if you want to cover mailing cost, PM me.

edit: factory crank gear also...amazing what ya find while cleaning off the workbench. PM if you want them. I threw out the chain or I'd just reproduce your measurements.