I have bought Toyotas for years, and really never had any issues worth mentioning.

This sound like a piston knock, and I sure hope it is not a rod bearing or worse. It does not occur at any given point in time either cold or hot and seems to come and go during my driving. I drive this car around 1,000 miles per week mostly on interstate.

I babied it during break in, and have always used Mobil 1 synthetic oil per manufacturers weight recommendation. I have not taken to a dealer since the car runs fine other than this seeming piston slap. However I wonder if I will get the 300,000 miles or more out of it that I have with my other Toyotas.

I drive around 50,000 miles per year.

It has been annoying but we will see how the car holds up in the long term.

I picked up my new 4runner limited on Monday September 15th 2014 at Penn Toyota in Greenvale NY. On wednesday September 17th, 2 days later, I started up the 4runner, let it warm up for about a minute, put it into drive, and KNOCK KNOCK KNOCK for about 15 to 20 seconds.

I brought it over to Toyota to the service department on friday the 19th, and was told its normal. I was told "the new engines in these toyotas have forged piston heads, due to their expansion rate, the diameter of the heads are smaller that the cylinders, so you're just hearing the heads slap against the cylinder walls, once the engine heats up the heads will expand and the noise will go away.. Don't worry about it"

So I had the service manager show me another 4runner on the lot brand new to try to replicate the noise. Guess what...nothing

He said he's going to contact HQ monday the 22nd to get a task case number so an engineer from Toyota can come out and take a look at the engine, which may take a few weeks to 2 months.

When I called Toyota HQ myself earlier today, the 20th, they could give a sh*t about the problem. They said "any problems, take it up with the dealership." Thanks a lot Devin from Toyota HQ

Being only 2 and a half days old and now sitting back on the dealership lot, I WANT MY MONEY BACK Now I'm without a car, out $10,000 that I put down on the vehicle, and out of patience.

Update from Dec 13, 2014: engine knocking has ceased at around 900 miles. There are currently 2400 miles on the odometer. The knocking can no longer be replicated even on the coldest days upon start up. Toyota has offered an extended warranty through 2022. If the noise comes back I will do another update.