getting a strange chirp sound at low revs & light throttle

[Sky-drive]

I noticed over the weekend, with the roof and windows down, there is a high pitched "chirping" sound coming from the engine on my 2.5. Only happens momentarily as I lightly load or unload the accelerator pedal when cruising in built up areas and its only audible at low revs. Under heavy acceleration the sound is definitely not apparent. Its not affecting performance of the engine and the sound isn't initially there when the engine is started up from cold and driven off. It does take a couple of minutes as the engine warms up for the noise to present itself and it can be heard in all gears including reverse. Any help or thoughts as to where I should start looking?

 

[Roundozo]

Always hard to diagnose a sound on forums. You could try checking your belts and tensioners as these might squeal when worn. Apart from that my only advice would be to ask someone to rev the engine etc and you to have a listen under the bonnet. However if this noise only makes itself apparent while moving I strongly advise against that plan! :wink:

 

[paddy wright]

Could be a crack in your intake boot- follow the air intake pipes from the filter housing back to the engine block there is a secondary small hose that comes off the main one that is well known to split.

 

[Sky-drive]

thanks for advice, the car has just had two new belts and a tensioner fitted so I'm confident the chirp is not coming from there.

Always hard to diagnose a sound on forums. You could try checking your belts and tensioners as these might squeal when worn. Apart from that my only advice would be to ask someone to rev the engine etc and you to have a listen under the bonnet. However if this noise only makes itself apparent while moving I strongly advise against that plan! :wink:

 

[Sky-drive]

cheers for advice, Ill pop the bonnet in the week and take a look at the intake pipes as suggested.

Could be a crack in your intake boot- follow the air intake pipes from the filter housing back to the engine block there is a secondary small hose that comes off the main one that is well known to split.

 

[Sky-drive]

Update: Forza GB sorted fault today ... turned out the "chirp" was due to the air intake hose having a couple of splits in it. Fixed with a replacement pipe. Not happy with a BMW specialist in Gloucestershire who was paid to give my Zed an inspection and health check the first week I had the car ... whilst they advised the engine needed new belts, rollers, tensioner and brake fluid change they missed this despite me telling them about the noise ...