S3 Idle and Persistence of vacuum

[AGB-S3]

Late 2002 S3 Idle and Persistence of vacuum

Ive 'odd' idle problem , which Ive been chasing down for a while , everything is nearly 'ok' the idle speed is constant , but with a sight hunting and a hint of erratic firing ... turn the air-con 'on' and its very much worse quite lumpy . No error codes, throttle valve has been off and cleaned , new plugs , filters , oil etc .. runs fine at speed etc.

How long should the brakes hold on for , when the engine is stopped ? I loose servo in about 15 seconds Brakes work fine with engine running , sometimes give the impression of a slight delay ..

There is no vacuum reservoir in the system ?

From the various posts , this points to some form of leak on the servo hose ? any thoughts ? what is likely to need replacing ?

The hose assy etc part number's ?

Tnx-Graham

 

[Tom93]

Have you checked all the PCV pipes under the inlet manifold? Remember if its attached to the inlet manifold then it can see vacuum and boost, unless there some kind of valve before it. Might be worth looking into this:

http://www.audi-sport.net/xf/thread...catch-can-and-simplify-the-pcv-system.118021/

Ive done a variation of that just venting to atmosphere, which is a bit naughty.

 

[Lodhiz]

I too also have a very similar if not the same issue, but I have done a PCV delete (not running a catch can though), as well as renewing all of the boost pipes with silicon ones. When switching the climate control unit on, particularly when turning on the A/C, the idle will still be a little lumpy. I think I may already have a weak A/C Compressor unit, but that still doesn't explain why on idle it hunts for rev's (ever so slightly).

 

[AGB-S3]

Thank's - Q , Brakes , how long do your brakes hold 'on' when the engine is stopped ?

I see about 15 seconds and the servo has stopped working, which , to me , seems odd, re start the engine and the servo is restored in about 5 seconds .. I don't know if there is a one way valve built in the servo or there is one round the manifold area .

But That must be a leak in the system ... one valve to servo , ie the pipe assy , worst case the servo is leaking ?

 

[ayfreetee]

Also check your tip, one of the vacume hoses on mine had split , which was a good excuse to fit a silicone tip.

 

[AGB-S3]

Im thinking , getting the vac system leak [ smoke] tested is going to be the only way ahead on this ?

 

[Clarky320]

Hi all,

Hoping someone might be able to help. I have an s3 8p 2008 and noticed last few days when idling the revs hunt between 800 and 1500. There's a loud hissing from the front of the engine bay and as soon as I take the oil cap off hissing stops. Guessing a vacuum leak from a split hose but curious how easy it is to get to that area behind the rad from below as I can't access it from above. Any help would be massively appreciated as I'm stuck in Italy for the next two months and would rather not take it to an italian garage as my italians shocking! Thanks in advance.

 

[<tuffty/>]

Hi all,

Hoping someone might be able to help. I have an s3 8p 2008 and noticed last few days when idling the revs hunt between 800 and 1500. There's a loud hissing from the front of the engine bay and as soon as I take the oil cap off hissing stops. Guessing a vacuum leak from a split hose but curious how easy it is to get to that area behind the rad from below as I can't access it from above. Any help would be massively appreciated as I'm stuck in Italy for the next two months and would rather not take it to an italian garage as my italians shocking! Thanks in advance.

You need to post this in the 8P section mate... you will get a better response

<tuffty/>