My car is doing pheasant impressions....

[Green Whale]

This may sound like a bit of a piss take but I've noticed my T5 makes a strange whistling/warbling sound, quite similar to a pheasant, when you blip the throttle when cold.

It only does it when the revs drop back down to idle and only when it's completely cold.

I'm not sure if it's related but I've also noticed an inconsistent throttle when holding revs, it sort of surges but on a very small scale under load.

I'm thinking it's either boost hoses or vacuum pipes.

Any thoughts?

p.s. I'll try and get a video as the description doesn't really do it justice.

[Green Whale]

There you go, that should help.

[TenaciousC]

Doesn't sound anything like a pheasant!

[TenaciousC]

http://www.volvo-forums.com/t42305-intake-whistle.htm
Similar issue in description. Said it was the pcv vacuum line which comes off the inlet manifolđ under the thermostat housing.

[Dangerous Dave]

I had a similar noise, as above it was the elbow on the vacuum pipe at the thermostat end of the inlet manifold. It had perished to the extent it was collapsing under vacuum and causing the whistle. Worth checking as its a quick fix.

[Green Whale]

My pcv has only just recently been replaced so I'm hoping it's just come loose somehow. That would also explain the warning light that won't go away.

Thanks chaps

[Green Whale]

Just had a quick look and the elbow piece mentioned is still firmly in place and not perished or damaged as far as I can tell.

Listening to the car on idle and when building revs it might be the line that goes from what looks like the wastegate to the idle control valve (could be well off there though.)

I'll need to have a better look when the car isn't still warm and it's not dark out.

[Shadow]

im getting the same noise as you only when cold and when the revs drop. iv read some where the it can be the oil thermostat bolted under the crank pully when the o rings start to go. my car's been doing it for years but only when it's really cold.