revolution indicator weird

[zako]

hi i'm getting a problem for the last months and no mehcanic is able to solve it. my problem is that when driving the car and it is at neutral state the rpm indicator accelerates by itself and comes to its normal position, duration time 1 or 2 seconds with normal temperature engine. can anyone help please

[citronut]

hi and welcome
can we have more info on what model/engine this car is,

and dose the engine's RPM rise with the REV counter,

regards malcolm

[zako]

my Xantia is an 1.8 16 valve engine. and no the revloution stays the same only the rpm moves up for 2 or 3 seconds and comes to normal again

[quintet]

Contrary to me actually owning one (note av pic) xantia's are a bit before my 'citroen' experience time but i would suspect your car has an issue with the soldered joints on the back of the dash binnacle causing erratic operation, the smallest of cracks could cause this sort of fault. If you have a dash binnacle with the old style km/mileometer you may get away with doing a swap with a 2nd hand one but I'm guessing yours is a later model with the digital km/mileometer & i don't think you can swap these, (mucks up the mileage readings).

I think it's ok to repair these by re-soldering the original solder joints but obviously this is a delicate piece of equipment so you'd have to be careful.
Has anything been replace on your car so far in a bid to try and fix this (you mentioned other people have had a go at it), I'm not sure where the rev counter gets its signal from, crank or cam sensor, these or the associated wiring could be at fault.