I have changed my idle control valve for my peugeot 406(petrol) and my car rev still goes up and down.?

My car's rev is up and down when my car comes to an idle position or stops. Even the mechanic don't seem to know the solution.I have changed my idle control valve for my peugeot 406(petrol) and my car rev still goes up and down.?
check for a vacuum pipe off sucking in air...also ask the mechanic if its a multiplex 406...the BSI unit may need reset....it may be as simply as disconnecting your battery for 3 mins,reconnect and switch on lights...this resets the BSI....then drive it for 15 mins till the ecu relearns you driving technicsI have changed my idle control valve for my peugeot 406(petrol) and my car rev still goes up and down.?
Read this info:


Peugeot Common ECU Failures


PEUGEOT 306 1.4 / 1.8(16V) and 406 1.8(16V) MODELS FROM 1997 to 2002 - IDLE CONTROL PROBLEMS. SAGEM SL96 (3 row, 55 pin) ECU suffers from damage to idle control CAUSED BY DEFECTIVE COILS. Replacing ECU WITHOUT REPLACING COILS WILL RESULT IN NEW ECU FAILING WITHIN VERY SHORT TIME FRAME.





Sagem SL96 Symptoms


1) Car suffers idle control problems manifested as rough running at idle and stalling at traffic lights.


2) Check engine light usually illuminates with coil pack fail and idle control fault codes.





Diagnostic Checklist


1) Check fault codes - if fault code does not identify which coil has failed, REPLACE BOTH. Coil failure almost guarantees ECU failure but run car with new coil(s) - if idle control is correct - and idle control fault code does not reappear then ECU has probably survived.





Your coil packs will need to be replaced, if your lucky the ecu wont have been damaged.
Check for blocked pipes from the idle valve air intakes and also check the wiring on the idle valve, and spray some carb cleaner into the idle valve and let it soak in for about 30 mins. Then try it again. Also make sure there are no air leaks where the idle valve is fitted. It could also be a air flow meter problem.
it does sound like you have a problem on the air induction side of things, has the mechanic had a very thorough look at all the vacuum pipes and even the inlet manifold gasket, some times all that is needed is a good clean out of the air idle Control valve. Good luck.
A engine that wont idle properly sounds more like a blockage in the fuel system


what year is the car?


if it has an ecu the problem could be with one of the sensors