Fiesta Zetec S Tdci. Rough Running On Start Up

[Gaz1984]

Hello

I've got a 2009 zetec s tdci and recently it's started running rough on start up when cold. It coughs a little blue smoke when you first fire up which clears after around 2-3 seconds and it's lumpy idling but clears itself and runs fine once you start to drive it. I've just changed the glow plugs which has made a slight difference, less smoke and little better on start up but it's not totally fixed. Anyone know what the problem might be?

Many thanks

[supercmaxer]

Is it surging when it does start, how many times do you need to turn the key for it to start?

[Gaz1984]

Surges maybe once or twice, and always fires on the first turn of the key. Tends to be happier with the screen clear button pressed (obviously because that puts a little load on the engine)

[supercmaxer]

I'm having the same problem, it doesn't always start on the first key, surges badly but starts the second time once it starts it's fine.

A few people have said it could be the butterfly known as the throttle body, the butterfly gets stuff when you turn of the car and is meant to open when you start it but becuase it's closed it doesn't have enough air being drawn in to the engine and therefore surges.