1.8t auq hunting on idle only when warm ?

[Dan20v]

As in title the revs are moving up and down slightly when its on idle and car is warm its fine when its cold i just done . Plugs.coil pack .pvc breather hose . Thermostat .temp sensor and had car on vag.com no fault codes . I thought it was the pvc breather hose as it had about 7 holes in it but no .

 

[matty85]

You could try unplugging your MAF

 

[Dan20v]

I bought a new maf last week a bosh one as well

 

[cuprastoffs]

Sounds like a vacuum leak, did you replace the whole Pcv system?

 

[mty12345]

Sounds like a vacuum leak, did you replace the whole Pcv system?

+1, have a look at all the vacuum hoses around the manifold.

 

[Dan20v]

There is i split in the vacume hose on the bend coming out the inlet manifold but just taped it up because at the weekend i going to do the bypass thing were you take yhat pipe out of the pcv for smoother boost etc maybe i see what happens at weekend . But why when i put the aircon on it runs fine but turn it off it goes back to wanting to cut out and **** idle ' only when warm '

 

[mty12345]

When you switch the aircon on (or anything else that takes a lot of power) the ecu ups the idle speed a bit to compensate. I expect the slight change in rpm is pushing it beyond the point where the idle is lumpy.

 

[cupraslayer]

I bought a new maf last week a bosh one as well

Doesn't mean nout mate. Mafs are very very temperamental . Most likely a leak in pipe work , but don't rule a faulty new maf out.

 

[Dan20v]

Replaced the maf abain i took it back said it was faulty . But still same problem . Some people said clean the throttle body and cheek vacum hose to it . Hard to do ? And when i accelerate i am hearing a boost leek sound but not sure if its the tubo spinning up hmmm can here it more now i got a standard air box on

 

[spanner87]

Is your temp gauge reading 90 when warm?or creeps down slowly when driving?I had this problem and changed the coolant temp sensor for a new genuine item and the problem dissapeared.

 

[Dan20v]

I done the temp sensor and the thermostat it runs fine on temp sits at 90 all day dont move when driving

 

[mty12345]

What sort of rpm's is it hunting between when it does it mate?

 

[Dan20v]

When cold'ish its running 850 rpm and stays there then when warm it goes to 800 rpm and can go down to about 700rpm and the lights flicker like it wants to stall .

 

[cuprastoffs]

How many ports are on the bottom of your inlet?
There should be four, two 8mm and two 3mm.
It really sounds like a vacuum leak to me.

 

[mty12345]

How many ports are on the bottom of your inlet?
There should be four, two 8mm and two 3mm.
It really sounds like a vacuum leak to me.

+1, my money would still be on a split or leaking pipe somewhere too.
Elsawin says idle speed should be between 700-840rpm, so it's staying within limit but obviously just having trouble keeping it stable.