Help!!! engine keeps over revving when idle

[BiggaG]

Lately my 07 tfsi vrs has been acting weird and keeps over revving up to occasionally 2500 but most times 1500-2000 then drops back down to under 1000. But this always happens when the engine is hot. I've taken it to a garage the  guy wasn't too sure but reckons it could be the idle control valve. Iso there anyone out there who could shed a better light this

[zavisa]

Same problem but 1.9 tdi, revs to 1100-1200 for 10 minutes and than back to normal. Solution is to change battery! To weak and it has to charge more. In my case that was solution

[meaty101]

Mine doesn't rev up but it does have an uneven tickover a little judder is the best way to describe it. Like yours only when the engine is hot. Having scanned for faults and not finding any it could be carbon deposits building up on the inlet valves. You could try removing the throttle body and cleaning it. Maybe take the plugs out clean those up. Can you hear any leaks like a pipe has came off? It could be a vacuum leak somewhere. 

Edited 19 February, 2017 by meaty101

[Papfox]

I had a problem with my vRS juddering back and forward like that at idle. It did it from when I got it second hand.

 

I asked the dealer to give the car a through shake down when it had its first dealer service after I got it. The Octavia uses "stretch bolts" to hold the engine in. These stretch the first time they're done up to give a "better than tight" fit and, because of that stretching, they must only be tightened once and need to be replaced if they're removed as they don't go back to their "in the packet" length. The bolts aren't expensive, only a couple of pounds each. The previous owner of my car had been having it worked on at non-Skoda garages and dealer discovered that one of them had undone the engine bolts and put the old set back rather than replacing them. This meant that they hadn't stretched when put back, weren't tight enough and the whole engine was loose. The juddering was it moving on its mounts.

 

The cost of replacing 6 bolts that would have cost around £12 had the off-network garage replaced them when they had them out... £170 including labour.

 

I know this is a petrol engine but I did see the symptom you are reporting on a diesel I used to drive after I picked up a load of diesel that was contaminated with petrol. I don't know what the effect would be if you i mildly contaminated fuel was introduced into the system. Did you fill it up just before this started? If it's bad fuel, it would quite likely be smoking as well.

Edited 19 February, 2017 by Papfox

[BiggaG]

5 hours ago, meaty101 said:

Mine doesn't rev up but it does have an uneven tickover a little judder is the best way to describe it. Like yours only when the engine is hot. Having scanned for faults and not finding any it could be carbon deposits building up on the inlet valves. You could try removing the throttle body and cleaning it. Maybe take the plugs out clean those up. Can you hear any leaks like a pipe has came off? It could be a vacuum leak somewhere. 

Haven't heard anything but when it starts revving and drops down it either drops to 1000  or below and run lumpy, the other day it was running like that and I went 10 miles down the motorway and when I came off it was well behaved

[James@RRG_Skoda_Rochdale]

PCV Valve? A very common issue on the TFSI engine 

Edited 19 February, 2017 by James@RRGRochdale

[BiggaG]

3 minutes ago, James@RRGRochdale said:

PVC Valve? A very common issue on the TFSI engine 

PVC valve? So the idle control valve how much is one of those would set me back?

[James@RRG_Skoda_Rochdale]

PCV valve (stupid phone!) 

 

It's not an idle controller it's a regulation valve for the crankcase breather gases, they sometimes stick and allow excess breather gases through that can raise the engine speed and bring on the EML. 

[BiggaG]

2 hours ago, James@RRGRochdale said:

PCV valve (stupid phone!) 

 

It's not an idle controller it's a regulation valve for the crankcase breather gases, they sometimes stick and allow excess breather gases through that can raise the engine speed and bring on the EML. 

Do you know how much they cost?

[BiggaG]

2 hours ago, James@RRGRochdale said:

PCV valve (stupid phone!) 

 

It's not an idle controller it's a regulation valve for the crankcase breather gases, they sometimes stick and allow excess breather gases through that can raise the engine speed and bring on the EML. 

Do you know how much they cost?