Hi. I had a k and n air filter fitted to my fiesta. I recently got the software update to improve starting which this worked but now it is more noticeable when the engine is warm coming up to a round about or just slowing down in general the engine revs struggle n most of the time cuts out.
I have recently put the standard air box back on but unfortunately have broken my foot so unable to test it. My dad took it out and said the engine revs did drop but didn't cut out so I have to wait and see when I can drive again.
I didn't know if there was a common fault with fitting a air filter like this?

try a ecu reset its worth ago

I fitted mine and not had any problems
what's this software update you're on about?

There's a software update for the ecu for Starting the engine. On the old sts like 2005 the engines struggled starting and just needed to blip the throttle for it to start. I don't understand why it keeps cutting out. If it's rolling still I just lift my foot off clutch to bump start it but if I'm stop I have to sit there n start it again. Makes me look like I keep stalling it.
Could it be unmeeted air getting through? Or not enough cold air feed? Or something else?

How do you do a ecu reset? Do it yourself or at dealership?

I have a similar proplem if I give the engine a little rev or a little sudden movement the revs drop but it's only cut out twice

turn off the car. hold the button down at the end of the indicator stick then turn the engine whilst still holding it down. eventually all the dials go round and the lights come on etc then you can keep clicking the button to try different tests it will say test or something on the display
worth a go?
not sure what that upgrade was... haven't had that done to mine

Mine does it all the time. Once it's up to temp is every time I stop. I don't have a button on the end of my indicator stalk is that a facelift thing?

yeah it might be actually not sure how to do it on the pre facelift sorry mate :S

My was pi$$ing me off last week. Cut out as I was going along at traffic lights!
Stopped it now though
Was thinking about cleaning the throttle body or chopping it in for the Mk2 F but it's ok now
WEIRD CARS SOMETIMES

Well ive put it back to standard but I do preferably want it on as it sounds nicer. I'll try it when my foots better n see what happens.

Cool keep us updated. The engine actually works and breaths better with a K&N So worth putting it back on, on a warm afternoon

yeah don't fit it at 5pm when it's getting dark like I did

Lol ok. Well I'll keep you updated cheers for the help. I can't work out why else it would be cutting out.