apl175

For whatever strange reason the diesel aficionados enjoy hearing such things...here's 2.5 minutes of engine idle, in a very high quality format.

The idle timbre changes slightly at the one minute mark, either due to idle compensation for cooling fan/AC compressor or because of the start of a burn-off cycle of one of the emissions devices.

http://www.youtube.com/watch?v=Dk7FwKCFn5k