I bought a 2005 Acura TL back in October 2005.  From the time I picked up the
vehicle, the engine always ran rough until it warmed up.  It clattered
something terrible in the mornings.  I attributed to the thin oil and the car
not being broke in yet.  As I had gotten several hundred miles on it, the
engine sounded the valves were justing floating and knocking.  Kind of like
the pistons didnt have quite enough clearance on the compression stroke
possibly some carbon build-up or a weak oil pump.  It was very obvious from
1700 to 2300 RPMS.  The noise persisted everday anytime I drove the car.  It
sounded like an old Honda whose internals parts were just wore out.  It
maintained good acceleration and passing power.  I never dogged the car once
during the break-in period.  I had taken it to two dealerships and had many a
tech ride with me and they couldn't not hear the noise and I was very atuned
to it.  It started driving me nuts.  I didn't pay $37,000 for a car to sound
like it had 70,000 plus miles.  The technicians said continue to drive it.
If the engine ceases or fails, Acura will replace it no questions asked.  I
finally got disgusted and called the dealership.  They gave me a very good
trade for my TL and put me in an MDX.  I love the vehicle and the room and
have more power than the TL.  Guys, give me your thoughts on this engine
issue.  I had owned a previous 2005 before this one (I wanted the new 2005
because I wanted NAV) and purred like a kitten and ran flawlessly every
morning with no ping, knock or anything.  Maybe this was just a bad engine
waiting to fail -- without my ownership.