C4 1.6hdi 2013 (B78) rough idle no codes or smoke

[kingjafad]

Hi Folks, I am hoping for some inspired inputs to get me going again please.
I have a C4 Picasso 1.6hdi 2013 (B78) and its recently start to have a rough idle, but seems to be running fine at speed. We notice it more when coming to a stop at lights/Junctions etc. I have had Diagbox and Think Diag on it and no fault codes but when looking at live data the Air system shows a couple of things I'd like to double check.
The air metering valve position and setting never change from 0% and the Open Cycle ratio for Air Mixer Electrovalve always stays at -4.5%.
All the other data PIDs change with revs.
I made an assumption that the air metering valve was the 'Air Doser/Mixer Genuine 1.6 HDI DV6 Air Mixer Unit Assembly 9673534480' which is basically a motorised circular valve the diameter of the air pipes on the top left of the engine (looking from the front of the car). I tested it via Think diag actuator tests - it moved to a couple of different positions then went to default of wide open - no errors came up. I found a scrappy replacement anyway just in case and fitted it, its exactly the same.
Am I barking up the wrong tree with those 'air metering valve positions' being 0 and the open cycle ratio being -4.5% for the cause of a rough idle and that that relates to the 'Air Doser'

The Measured Air Flow fluctuates when i rev the engines so assumed the MAF is working fine (unless someone tells me the 254mg/impulse at idle is not correct)

VIN is in screenshots.
Many Thanks,

[RichardW]

The mixer valve is only activated when a regen is called far AFAIK. I suspect you have an injector (or 2) that is going wonky. My 3008 vibrates a bit at idle, hasn't really changed in 50k miles, so I just ignore it!

[kingjafad]

Thanks Richard,
The wife has a few long runs in it coming up so will get feedback from that to decide if I simply keep an eye on it for a while. (having recorded the Injector figures, I can compare at a later date) At least I now know its not a snag with that mixer so I am not chasing myself. I am fairly proficient at injector pulling/replacing/coding now so it wouldn't scare me if I needed to do it (have slide hammers and a pneumatic vibrating puller too that I used on an extremely stubborn injector in a C4 Grand Picasso a few months back)

[kingjafad]

Update:
So it turns out it is possibly a Dual Mass Flywheel starting to fail. With clutch engaged on the flywheel, no wobble - acceleration is fine, no misfires etc. Only when clutch is not engaged on the flywheel or in neutral does it do the 'wobble/rough idle'. Also recently there has been occasional screeching when starter motor tries to engage, my theory is that if the ring on the DMF is slightly in the wrong angle due to wear of the DMF, it fails to engage. I let the clutch off and press again and it starts fine (i.e. pushed something against the DMF to realign it) I have it in the garage at the moment to confirm (logically i am thinking taking the starter off will allow access to the DMF/Ring to feel any play beyond what it should be). I'll update this thread when i get a solution

[Paul-R]

What's the mileage of the vehicle?

[kingjafad]

105K - never had a clutch....yet

[kingjafad]

FIXED
It was indeed the Dual Mass Flywheel. I got the whole clutch/slave cylinder/bearing replaced at the same time as it was mostly a labour intensive job and my thought was that it will never need to be changed again in this cars lifetime then.
So nothing to do with injectors etc. Car has been running absolutely smoothly since the DMF/Clutch was done. If anyone else comes across this, the clutch was definitely not slipping at all, it was just the DMF
Hope this helps for anyone else in the future.