I own a 1999 Felicia Fun 1.6 mpi which has always run perfectly well in all conditions. Recently I have started having trouble in damp conditions with it developing a misfire at times causing the engine to cut out completely and not re-start until it has dried out. To cure this I have fitted new plugs,leads, cap and arm plus I have tried to waterproof all plugs and sensors in the engine bay with no joy. Two garages have now looked at the car with no clear answers except the throttle position sensor showing a repetitive fault, this has now been replaced along with the coil but the cold start problem seems to persist. The engine will start momentarily from cold but dies almost straight away, after 3 or 4 attempts it will start but runs lumpy at about about 800rpm and dies if you are too quick on the throttle, once warm it doesn't seem too bad although I'm not sure it is altogether right. If anyone knows what this could be please help as I'm tired of being told what it can't be instead of what it is.

Most likely a fault with the hall sensor in the distributor.

^^ yeah, what that geezer said

in the back of the distributor behind the black plastic cover is the hall effect switch, the engine management uses this to work out how fast the engine is turning and to determine the TDC reference for spark timing... essentially it's just a magnet, and when the fins on the trigger wheel pass it induces a small magnetic field across to the sensor, and hence a current flow :yes:

when they get damp they don't work very well if at all, and sometimes the magnet gets a bit corroded which makes the signal weak.....

what you can do to try and fix it, is pop the cap, arm and plastic cover off (make sure you make a diagram of where the ht leads go before you start) clean up the magnet with a piece of coarse sandpaper to get rid of any surface build up, then spray in some wd40 to drive the water/moisture out.

also there is a rubber o-ring that seals the back of the dizzy from the camshaft, sometimes these get a bit tired and allow some oil to seep through to the sensor which causes a misfire....

a new dizzy from the dealer is about £150 if i recall plus they will want your old one as a core for exchange, but if you get one off a scrapper you can use one off a 6n polo or seat ibiza with a 1.0/1.4/1.6 engine they are all the same..... there are 2 types across the range though, the magneti-marelli ones have a black dizzy cap, and the bosch ones have an orange dizzy cap, you can use which ever type you like but the rotor arm and cap are specific to the type of dizzy you have, so you need a matching set of dizzy, cap, and rotor arm if that makes any sense

Edited 12 January, 201016 yr by TeflonTom

you can buy a repair kit for the bosch ones too, just a thought have you changed the fuel filter ? most fuel stations are now on biofuel and this stuff is very prone to blocking filters due to it absorbing more dirt from the tanks etc than the old stuff, its caused our fuel dispensing pumps a headache for a month now

Thank you all for your help, my fun is going in to Skoda Monday for a new fuel filter, and to have the hall sensor and distributor investigated and cleaned up, fingers crossed. Thanks again Simon