Engine cuts out when stationary.

[PitstopPete]

My 2007 1.6 petrol focus is cutting out when stationary, everything cuts out, the steering goes heavy the engine turns off. It has only done it once while moving, and I wasnt going more than 10mph. But when stopped at lights, or junctions it is happening quite a lot. After a few turns of the key it starts up again. I did have a few electrical problems before so I changed the battery and most of the problems cleared up, except for the cutting out and every now and then all the lights on the dash light up for a few seconds and then go off again. Does anyone have any ideas, as this is stressing me out, and I need it fixed. One idea is it could be the idle control valve, anyone else got any ideas???

[JohnF]

It might be carbon/dirt build up on the edges of the circular butterfly valve in the throttle body, which is designed to not quite close the circular tube bit of the air intake so the engine can breathe when idling. If too much carbon is deposited it will virtually completely seal the air intake when the accelerator is not pressed.    Our Focus was occasionally cutting out when coasting, and the EML was occasionally coming on,  so I removed the rubber intake hose and cleaned the edges of the white plastic disc butterfly valve and it's been fine ever since.

[PitstopPete]

Ok thanks John, I will give that a go before I try anything else.

[PitstopPete]

I have now fixed the problem. The battery was not holding a good enough charge, I think that caused a few electrical problems. Also the ignition switch was the cause of the stalling, I changed it for a new one and all is good.