Odd idle speed behaviour

[FarmerPug]

My 406 (2.2 HDi) has a bit of an issue with its idle speed.

Normally it sits at about 900-950 rpm but if i move the car and freewheel then brake the revs dip down to 600 rpm as if its about to stall.

This would happen for example when reversing out of a parking space; the car is put into reverse, it backs out and when it has went back enough the clutch and brake are pressed, the car will then dip its revs to 600 rpm before returning to its normal idle speed.
the same happens if slowing down coming to a junction. It hasn’t stalled but it feels as if it is about to.

I thought perhaps the clutch wasnt disengaging fully when pressed down but this also happens if the car is put into neutral in these instances.

[rwb]

Could it be related to the clutch switch?
IIRC it has something to do with cutting revs when you disengage the clutch

[steve_earwig]

I think it does the opposite, if the clutch is dipped while the car is moving it raises the idle. I think

[GingerMagic]

Yeah, sounds to me the clutch switch isn't connected - I had the same symptoms on an old hdi90, after I unplugged the clutch switch.....
Is cruise control working?

[FarmerPug]

The cruise control works every time, on my old 110 it worked most of the time

Might need to get pp2000 plugged in, the clutch itself seems to sink after a few days of driving the travel becomes reduced, requiring it to be pulled back up with the foot although the actuation of the clutch seems to still be ok.

[Doggy]

Normal idling speed is about 820 RPM on the tacho, or 790-odd via PP2k, (with the aircon turned off).

Maybe there's something odd with the ecu map - (I gather you may not know the origin of the one it's using)?
I can compare it with the 'normal' one if you want.