From: Phil Payne 

> (IME Audi 5 cylinders clearly sound like they're not 4s or 6s....)

If you kneel in front of an idling engne with the bonnet open, you can get
so adjusted to the rhythm that you can start to make out the individual
cylinders and valve followers.  Usually takes me ten or fifteen minutes.
Blows the owner away when you turn round and tell him his #4 inlet lifter
is collapsing.

--
  Phil Payne
  http://www.isham-research.com
  +44 7785 302 803
  +49 173 6242039

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