Rev increase and rough idle

[P44ABF]

Just wondering if this is normal or if anyone can point me in the right direction if there is an issue.
Its happened for a while now but its starting to annoy me, when im in stop start traffic especially if its a hot day the revs will increase by around 200rpm and it will just feel kinda rough, and then when selecting D from N theres a slight jerk.
Even on a normal day i can feel a slight vibration but ive been told thats just the V6 etc,
Any help would be nice cheers

 

[IRONy_MAN]

Dpf maybe?from 800 rpm to 900-950 for 15 mins? try to see if you find something in common for time you see the car behaving like that

 

[usmanrrana82]

What engine?

Sent from my SM-G928F using Tapatalk

 

[P44ABF]

Sorry its an S4 B8 S-tronic 3.0 supercharged

 

[Chilly]

Could be a lot of things, but to me it sounds like a vacuum leak on the inlet side. Engine is attempting to correct the mass flow and causing the rough idle.

Had it on our s3 on the vacuum line to the brake booster ...... Not sure if it's common on the S4.......... and before anyone says, yes I'm aware they are different engines, however the principle is the same forced induction combustion engine with similar ancillary components.

Best of luck.

Chilly

 

[P44ABF]

Ah right okay, i suppose thats a start i'll look into it thank you

 

[Chop.]

The s4 v6 has always felt a bit lumpy to me

As above or plugs maby ?

I do find the stronic can be a bit jerky from D to N etc sometimes and 1st also

 

[mdmay]

mine does the same if it has been in traffic for a while. The revs raise by about 200rpm and the DSG can be jerky i believe the rev raise maybe to do with the engine heat and it adding more fuel for cooling