[MarkR171]

Update Tuesday 9/27/16.

Got the car back today.

The service manager had me speak directly with the tech to go over everything they did with the car. The first thing they did was unplug the controller for the driver side exhaust cam gear. Immediately, the knocking/tapping noise stopped. Toyota had them drain the oil, cut open the filter to look for debris, and even ran some oil through paper to look for debris. They found nothing. They refilled the oil, plugged the controller back in, and no more knocking/tapping. Engine runs perfectly normal.

Toyota believes there might have been a tiny bit of debris in the oil control valve that controls the oil pressure inside the cam gear to control the timing. By unplugging the controller, and plugging it back in, they think they forced the debris through the valve. They didn't want to open the timing cover because there is no longer any symptom to diagnose. Opening it and looking around would get them nowhere.

I asked the tech if there was any oil left that could be used for an analysis, but he said the oil has been out in open air so it wouldn't be a good idea. But he did mention it would be a good idea to do an oil change after 3-5,000 miles and send the oil out for analysis just in case there are particles that the naked eye can't see.

For now, the dealership put 107 miles on it since the noise went away and I put about 50 on it today. Car is back to normal.

I'm somewhat relieved that it seems to not be a mechanical failure. Everything that has been done to my car has been logged to my VIN with Toyota so it's all documented in case the issue comes up again.