Lumpy Idle issue

[ChazGTI]

Been trying to diagnose this for a few months. Spoken to a few other people with the same problem.
She idles like this (no rev change) when cold and warm. I hadn't changed anything recently when I first noticed it. Goes away after revs rise past 1k and engine performs well across all gears etc. She does sometimes tend to be hesitant at low revs when cold, not sure if that's related.

Timing Belt, tensioners and water pump done 15k ago, just done cam chain and tensioner, Dev D Diverter Valve with GB DV+, Newish plugs and coils (all), Stage 1 map. Checked PCV and its solid, replaced gasket anyway. No codes on VCDS and no misfires.
Only thing the car really needs is fuel filter replacement, could that be it?
Want to get it sorted as it just doesn't sound healthy, although like I said, there's no problems after my foot is down.

[Ricky123]

Injector/s? Check them using vcds

Excessive carbon build up? Only one way to find out really..

Maf? Unplug it and see if there's any change

[pudding]

It does kind of sound like injectors.  The fuel pressure increases a lot when you put your foot down, so partial nozzle clogging isn't as noticeable there as it is at idle.  The misfire counter isn't great at idle speeds, so can take ages to register a fault.

I do my fuel filter every year.  Mainly because it's got a pressure regulator built in and when it gets weak, it can cause cold starting issues.

[r5gtt]

Check your hpfp cam follower as this is a common cause for this sort of behaviour especially when it's about had its life span and worn down to its limit.

[whitemoredooor]

Could be DMF is begining to fail.

[r5gtt]

Easiest way to check the pcv is to pull the dip stick up not out and if idle goes up and down its working fine, if it's remains stable it's failed so why you removed I dint know.
There's a pipe next to the hpfp that could be damaged?.  Pull it out it pops off and check it.

[ChazGTI]

Injector/s? Check them using vcds

Excessive carbon build up? Only one way to find out really..

Maf? Unplug it and see if there's any change

I'll have a look at the injectors then.
Unplugging MAF makes it run like crap so its not that.

Gonna try some wynn's engine flush and change the oil (obviously), not that oil change is due.

[ChazGTI]

Check your hpfp cam follower as this is a common cause for this sort of behaviour especially when it's about had its life span and worn down to its limit.

Not sure if I said so, but already replaced that recently. Old one needed changing, but wasn't that bad really.

[ChazGTI]

Easiest way to check the pcv is to pull the dip stick up not out and if idle goes up and down its working fine, if it's remains stable it's failed so why you removed I dint know.
There's a pipe next to the hpfp that could be damaged?.  Pull it out it pops off and check it.

Yeah I've checked the PCV thoroughly already. Its a later revision luckily. Just happened to have a spare gasket for it, so replaced it for peace of mind as the old one was looking a bit worn out.

The pipe by the hpfp is good.

[r5gtt]

The only other things would be as suggested your injectors or excessive carbon build up in the head which can only be determined via a borescope or removing the inlet manifold for a visual check. Sorry I can't help any further.

[Nico2904]

Timing set wrong after chain change? I have a similar problem. Just did chain and tensioner on I got power loss and lumpy idle. I can see with VCDS mine is out :/

[ChazGTI]

Timing set wrong after chain change? I have a similar problem. Just did chain and tensioner on I got power loss and lumpy idle. I can see with VCDS mine is out :/

Nah this was happening long before I did mine. How did you get yours wrong then? It's bloody hard to get that chain on wrong?

[ChazGTI]

Well the issue has become more apparent and its clearly the DMF. Sounds like a box of gravel when pulling away, almost disappears when pushing clutch pedal down at idle.

[ChazGTI]

Can confirm that most of this issue was down the DMF. My Crankshaft pulley also seems to have play in it which makes the belt tensioner panic at idle sometimes, which I'm investigating now.