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The wifes Hdi90 motor has a bit of a rough tickover, and judders like a tractor at around 1000rmp - hard to tell without a rev counter ( bloody Citroens.. )

I tried to use Lexia - which isn't a patch on PP2000 btw - but I couldn't access the injector values.

The MPG is down to 35mpg when I drive it, 31mpg when the wife drives it so I think there is a definite issue, I'm thinking MAF or injectors.

Any other ideas?

i would start with the rev counter as a bad of failing connection would give bad reading to the ecu or was the rev counter never there?

mafs don't normally cause juddering when they fail. could it be an engine mount? or the clutch dragging

is there any smoke when this happens? black, gray or white

Hi, car drives perfectly well except the rough idle and poor economy.

No smoke really, and Picasso's weren't fitted with a rev counter....

I might unplug the MAF and take the car down the bypass at a speed it isn't really made for, hopefully clear out some cobwebs.

If you can't access injector correction values, can you see the MAF reading? This wouldn't be conclusive, but when my previous one was idling badly with faulty a injector, the MAF reading was around 300 and very unstable, when I raised the revs to 1000/1100 the MAF value REDUCED and pretty much stabalised.

If you suspect injectors, do a leak-off test, costs next to nothing and gives you a good idea what's wrong.

Correct me if I'm wrong but I think that the MAF on the HDi 90 is only to monitor EGR function?

Not sure. 90's don't have MAP sensors as they have mechanical boost control, but I would have thought they would still use the MAF to calculate injection quantities.
(May also depend on whether we're talking Siemens or Bosch here)?

Ah yes if there's no MAP then I guess they must use the MAF.

I thought I'd remembered reading that somewhere but I can't remember if it applied to Bosch/Siemens (or is even true at all!).