RPM goes up and down by its on accord.

**nhogblom** · 05-08-2016 03:18 PM

Hello,

I recently bought a B8 2010 with 2.0TFSI 211HP engine & s-tronic 7 speed automatic transmission that has been on the road for 126000 km.
The engine was rebuilt with new pistons & new head etc by Audi last October for 85000sek(9200€~) due to excess oil consumption, which i thought was a great thing.

A few weeks after purchasing i started to notice that when my foot is steady on the pedal or when i use the cruise control the rpm jumps up and down on its by itself..
From what i have seen it only happens when the motor doesn't get any increase in throttle(?), for example it never happens going uphill, but when driving on plain ground or downhill the rpm lives its own life making the drive unpleasant.

Also when accelerating from a standstill it can be a bit jumpy, doesn't engage gear until 1000-1100 rpm and then loses to 900 and jumps away. And parking can be hard since it jumps when removing foot from brake pedal instead of edge along(?) it jumps a little bit to stop then jump again until either i brake or give more gas.
Today the motor stalled during parking.

I changed the PCV valve to a brand new one this Friday without any improvement, Changed it because i thought it was the culprit.

Scanned the car with a ELM bluetooth dongle and carista & torque pro app. No fault codes were found..
When removing oil cap when motor is on, it gets sucked back down again, so that shouldn't be a vacuum leak somewhere else?

Bought the car of an private person, so taking it back to the seller isn't much of an option.

The 120000km service of the automatic transmission was never performed from what i can see by the servicemanual/book, i have one scheduled for later this week.

Video i recorded of the problem with rpm going up and down, the jumpy part that i described is not on the video:
https://youtu.be/bv6QBld53UQ

Thankful for any help i can get.
English isn't my first language so don't go rampage for grammars please.

Thanks in advance
Niklas