S3 idling issue

[shinsplint]

Hi chaps,

Just had my S3 (2007) MOTd today, and its now behaving strangely on idle.

It is revving automatically to 1.5K - 2K rpm, then lowering back down, and repeating. I'm also hearing a fairly quiet but high pitched sound like a fan belt. When I drive it goes back to normal.

Any ideas on what this could be? I've been assured that nothing in the MOT could have caused anything like this.

Thanks in advance.

 

[shinsplint]

An update guys.

Left the car to cool over night. Drove for 45 minutes this morning without an issue, then briefly repeated what was happening yesterday - in neutral, revved up to 2K revs on its own, accompanied by a quiet high pitched whistle, which I think could be a belt of some sort. Only happened once then went back to normal again. Very strange !

I left the engine running for a minute or so when I got to work and it was fine. I did notice however, when I switch the heating system off, the revs drop very slightly. As though the heating system requires higher revs. This could well be normal I guess?

Any thoughts?

 

[Ads]

Sounds like a dodgy PCV. The common symptom of this is fluctuating revs at idle, between normal and 2k rpm, constantly repeating itself when the engine reaches normal running temperature.

 

[shinsplint]

Thanks Ads... if it is the PCV... how serious?

 

[MrLapou]

Sounds like an air leak more like a hose. Open the bonnet and have a listen, pull hoses etc..
PCV on your car's engine is dead easy to fit.

 

[Ads]

Thanks Ads... if it is the PCV... how serious?

Not serious at all. Quick and cheap'ish fix by any decent mechanic.

You can test yourself to see if it could be the PCV. Let you car get to normal running temp and try to remove the oil filler cap while the car is still running. If you can't get it off because of pressure then it's your PCV. Also try pulling out your dipstick to see if it sounds like a vacuum cleaner.

 

[shinsplint]

Cheers guys

I'm taking it to an Audi specialist later today so hopefully they'll sort it. Thanks again.

 

[MrLapou]

Let us know how you get on....

 

[shinsplint]

Well it is the PCV apparently, getting it done on Saturday. Hopefully all will be ok following that.

Cheers lads

 

[K.A]

Hi Shinsplint

How much are they charging you for the PCV work?

thanks

 

[shinsplint]

Hi Shinsplint

How much are they charging you for the PCV work?

thanks

Cost me £85 fitted for new PCV.