2003 3.2 TL idle rattling noise (exhaust?)

I have a 2003 Acura 3.2TL with around 5200 miles on it. I noticed that if
my car runs idle for a couple of minutes it starts making a rattling noise
that seems to come from underneath the car near the back tire on the
driver's side of the car. When it happens, It sounds as if there is a
pinhole in the exhaust or sounds as if there is a loose exhaust pipe.

The noise only seems to happen if the car runs idle for a couple of minutes,
and I don't notice it when inside the car. I just happened to notice it
when I was outside of my car talking to someone. When the noise happens,
if I press on the accelerator and rev the engine up a bit and then release
the accelerator the noise goes away but then eventually comes back. Again,
the noise is only noticeable when I'm standing outside the car and sounds
like a pinhole in the exhaust, or a loose pipe underneath the car.

Is the rattling noise I just described normal for Acura 3.2 TLs?

Two other observations which may or may be unrelated to the problem and do
not seem to directly correspond with the problem:

1) I also notice that when my car is idle the engine sometimes briefly
sounds like it is becoming more active for say 10 seconds or so and then
dies down to the normal speed. The tachometer does not seem to indicate
that the engine is speeding up when this happens. Is this normal.

2) If I open up the hood I hear a repetitive clicking noise near the back
of the engine compartment on the drivers side. I don't think the clicking
noise only happens when the exhaust rattling happens.

Anyway, I plan on bringing in the car to have it looked over. Any ideas
what the rattling noise near the back rear tire might be?

Thanks.

Jeff

 

Just to clarify...the noise seems to "tick" at a regular interval...in other
words not a random rattling..but as I said before it's the same type of
sound as if there were a pinhole in the exhaust...although...to me... it's
strange how it takes a couple of minutes before the noise happens...and...to
me...it's strange how reving the engine briefly will make it go a way
temporarily.

Jeff

 

How fast are the ticks? If they are at fairly long intervals (more than
half a second) and pretty loud and metalic, it could be your exhaust
expanding. All Honda's we've in my family had would tick after a drive
after turning the cars off (the metals cooling off and contracting). I'm
not sure it would happen when the car would be warming up though.

Another very common ticking sound on Hondas are the valves. Those ticks
are much faster and quieter than the metals expanding/contracting, and
they're (obviously) coming from the engine. So this is ruled out in your
case.

Your car is far too new to have a damaged exhaust system, and even a
pinhole in it would sound horrible. And it would definitely get much
louder as you would accelerate.

Cosmin

 

Jeff,
Cosmin made some interesting comments and I agree with everything he said.
I would just like to add that your Acura should still be under full
warranty and you should take advantage of this fact and let the mechanics
at your dealership fix these problems BEFORE the warranty period comes to
an end. Make sure you explain to the service writer the problems. It's
possible that there may be technical bulletins on your problems. After the
mechanics place your Acura on a lift--they should be able to easily figure
out if there is a problem with your exhaust system. I don't have a clue as
to the source of the clicking noise.