Buzzing from engine on cold startup - 1.8T

[richjthorpe]

Hi all,

I've got a B6 1.8T and just recently (Maybe due to the cold weather) I have heard a buzzing noise from the engine bay. It happens as the autochoke takes the revs over 1,000rpm and then dissapears after a minute when the revs drop to idle speed. When driving around normally, the noise cannot be heard.

I haven't lifted the bonnet to check it out properly but I can hear it at the same audible level whether I'm stood at the drivers side or the passenger side.

Anyone care a stab in the dark ?

Richie.

[Teutonic_Tamer]

Hmm - it could be a secondary air injection pump - used to help the cat heat up quicker?

[richjthorpe]

Where can of these be found ?

[Teutonic_Tamer]

Dunno exactly, but it could be tucked up inside the front wing, between the outer and inner wing.

If the noise is only heard on cold starts, and only lasts for about a minute, then that is perfectly normal operation. It's all to do with emissions, and getting the catalytic converters up to operating temperature ASAP. You shouldn't hear it on a warm start.

Rgds