06 TB Rough Idle and Whistle on Startup Cold
Hello, my 2006 TB with I6 engine has a rough idle and eventual "whistle" in the first 30 -40 seconds of a cold start.
The idle at first is ok, then gradually it becomes rough and sounds like it's missing, then it surges and it sounds like the air pump comes on, which is when it whistles and the idle settles out smooth again.
The dealer has been chasing this since November last year, so far replaced a check valve and air pump. The whistle is just a little harder to hear, but the rough idle is still there in the first minute after startup.
Anyone experience this problem or have any suggestions? I am trying to nip this in the bud before it developes into a worse idling problem as I have read in the forums here.
Any help or suggestions will be appreciated!