I know it's old news but I have a KA with a misfire

[ironhorse]

My daughter has a 2007 KA, she brought it over to me because it has started to misfire, as a matter of course I replaced the HT leads, took the car for a14 mile round trip in order to get the engine running at temperature, at around half way I stopped the car which up until then had been running spot on no misfire, I went into a shop then returned to the car ignition on and off I went again, only this time yes there was a misfire, a definite stutter as you went through the gears, I dropped a gear and foot down hard, it seemed to clear at high revs but as soon as I dropped off the pedal and drove normally the misfire was there again, my daughter tells me she has been into her local garage with this problem twice and twice they said nothing wrong, I am convinced this only shows up when the engine is hot. Can anyone point me in the right direction please.

[delboy]

sounds a strange one. i would have the altinator and battery checked first then let us know the outcome. hopefully its something simple to

rectify.perhaps its a coil pack thats playing up when it gets hot ?

[Omendata]

Hmm I have been struggling with a similar issue and its the fuel pump - Does your daughter frequently drive the fuel tank on low.

My fuel pump had worn and after driving then parking it would not start for 30 mins to an hour due to the fuel pump sticking.

Its a long shot but if the garage cant find it and its a problem that wont be picked up by an OBD tester that garages use!

Sounds like it could be an electrical issue though with cars ive learned that sometimes the most obscure thing can be the culprit!

As Delboy says coil or spark plugs - change em and see what happens - Seond hand Ka parts are cheap as chips on eBay just be grateful its not a Porsche lol

[AaronF]

I had a slightly similar issue on my previous Focus, it would "stutter" between 1.8k and 3k and above that be fine. Ended up being the fuel pump that was disintegrating by itself.

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[ironhorse]

Ok so I spent the last 3 days going over the car checking pretty much everything, I found the fuel return pipe was blocked, free that up car ran but still misfire, anyway after removing the air intake system, I found the problem the temperature sensor that also controls the fan, is completely shot to bits, the sensor just crumbled disintegrated creating a short circuit, and the misfiring, the temperature sensor is mounted on a plastic housing which acts as a junction for the water works, there are I think five pipes going into this unit of differing sizes, I had to remove the housing completely and when doing so this also began to crumble, after a trip to my local scrap yard and replacement part in hand for a tenner as opposed to £45 new, I fitted part turned key and car sprang into life and all is now well, So this may help someone out should they suffer the dreaded misfire problem, that not even my local garage could find.