Revs hunting at idle

[vala]

On idle the engine in my car is hunting and not staying at a consistent rpm. Under load the car is fine and the revs rise and fall as they should. It even stays ok when I shift into neutral for a brief moment after being under load. But if I were to stop with the engine running, within 30-60secs again the revs will not be stable.
I noticed last time I drove the car the red oil pressure warning light came on. I swiftly came to a halt however as the revs came down the light would go out. I've had this problem before and it was solved through a clean pick up pipe and a new oil filter.
I think during the intake camshaft change I did recently some dirt my have entered the engine whilst I was cleaning the mating surface on the head (this is noted in a guide from here) and on the first oil and filter change I did noticed some of the crap on the filter. I'll be doing another oil and filter change on Tueaday along with rechecking (and if need be, cleaning) the pick up pipe.

So could low oil pressure cause the revs to not be stable at idle?

 

[Smirky]

Changed spark plugs recently ?

 

[vala]

Spark plugs changed last December. Approximately 6k on them now.

 

[Smirky]

Could be a cheap fix

 

[audismart]

PCV valve, best way to check is to pull dipstick out with engine runing and if the is no difference in engine idle then its the PCV valve no venting.

 

[THQuattro]

Get the throttle body cleaned.

 

[audismart]

Get the throttle body cleaned.

Check PCV first, its a common fail.

 

[vala]

Here's 3 10sec videos which show the engine idling once it's started, after the revs settle from just over 1k (always happens on the first start with the engine cold) and when the engine is up to temp.
The idling IMO gets better once the engine is warmer but it still sounds rough.
With engine running and dipstick removed the engine sound remains the same.

View My Video
View My Video
View My Video

 

[audismart]

Yep new PCV. I take it your car is a VW from engine cover? Easy enough to replace, heres a vid.
VW Passat PCV valve location and replacement - YouTube

 

[vala]

Just done another oil and filter change plus cleaned the pick up pipe in the sump and the red oil pressure light hasn't appeared on the test run.
However plugged into my code reader and error code P0300 has come up and it's mentioned 3 there's a misfire on 3 of the cylinders.
Had a quick search and that appears to be related to plugs/coilpacks.
Although the plugs have only been replaced about 6k miles ago I assume it would be wise to replace these again?
Just waiting on TPS to ring back to confirm they have the coilpacks in stock.
I'll get a new PCV valve for it as well to eliminate that.

 

[vala]

audismart - it's a mk2 octavia vrs.

 

[audismart]

bwa engine I guess? Still its a 2.0tfsi all used in various cars.

 

[vala]

audismart - yes, still the BWA engine found in many VAG cars.

 

[vala]

Replaced the PCV valve on the rocker cover.
Still no joy, rough idling is still present.
In other news replaced all 4 coilpacks and 4 spark plugs and after a brief test drive plugged code reader in and no longer get the P0300 error code.
Anyone got any ideas as to the cause of the rough idling?
I have also noticed a kind of whirring/whistling sound on acceleration which definitely wasn't there before.

 

[audismart]

Well op said clean throttle body and I would give the maff sensor a pray with special spray, NOT WD40, and check for air leaks in the boost.

 

[vala]

Could air leaks in the boost system cause rough idling though?

 

[vala]

Also I did notice that when I have recently done work to the car on the last 2 occasions the car would require a jump start after.
Could a weak battery or failing alternator cause the issues I'm having?

 

[audismart]

Could air leaks in the boost system cause rough idling though?

Its all part of the intake system so yes.

 

[audismart]

Also I did notice that when I have recently done work to the car on the last 2 occasions the car would require a jump start after.
Could a weak battery or failing alternator cause the issues I'm having?

Not sure on that, but could be possible as when the car is asking for things like spark it wont get it fully or instantly.

 

[vala]

Problem solved!
Spoke to Alex at AKS with regards to getting my car booked in to have the issue checked. He mentioned a little part which went against the end of the intake camshaft held in place by the cam cradle.
Removed the timing belt cover and tapped it in, started the car and voila...car idles spot on!
At the time I was a bit baffled as to where this part went, and how it was secured as it must have been stuck to the intake camshaft and I only noticed it when it fell on the floor.

In this image you can see the black part clamped down by the cam cradle on the intake camshaft. That's what I forgot to refit when I changed the intake camshaft.

 

[JamesW1994]

Problem solved!
Spoke to Alex at AKS with regards to getting my car booked in to have the issue checked. He mentioned a little part which went against the end of the intake camshaft held in place by the cam cradle.
Removed the timing belt cover and tapped it in, started the car and voila...car idles spot on!
At the time I was a bit baffled as to where this part went, and how it was secured as it must have been stuck to the intake camshaft and I only noticed it when it fell on the floor.
View attachment 76054
In this image you can see the black part clamped down by the cam cradle on the intake camshaft. That's what I forgot to refit when I changed the intake camshaft.

Hey Vala, I am having the exact same issue as you have described! However I am struggling to see the part you are referring to. Can you annotate or zoom in and screen shot on the image the part I would need to check out. Thanks in advance!