Ford Fiesta Mk6 - Misfire on cold engine

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Fri 11 Jun 2010 09:29
Ford Fiesta Mk6 - Misfire on cold engine - graham3232

Car starts fine and drives fine for the first 30 seconds, then it starts to misfire badly when accelerating, although it’s not too bad if you accelerate very gently and slowly. It revs fine and idles fine. Then after a few more minutes and the engine has reached full temperature it perfect.

I checked the obvious stuff, the plugs are genuine ford from the dealer and are 4 months old, I swapped coil pack and leads with a mates car to check and no difference. There are no fault codes.

Any ideas?

1.4 Duratec 7 years old 145K

Thanks.

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Fri 11 Jun 2010 15:26
Ford Fiesta Mk6 - Misfire on cold engine - Peter.N.

A misfire at full throttle would suggest an electrical problem rather than fuel, you need a higher voltage to jump the gap when the cylinder pressure is high, although you say the plugs are fairly new they would be the most likely culpret. You could try closing the gaps a little, if you can do this, I haven't run a petrol vehicle for about 30 years so am not familier with modern ones.

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Mon 12 Jul 2010 22:43
Ford Fiesta Mk6 - Misfire on cold engine - grabbins

My 2003 Ford Fiesta 1.4 LX is having the exact same problem as you are describing here. Did you ever find out what the problem was? It just started doing this last week.

Greatly appreciate this.

Thanks.

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Tue 13 Jul 2010 23:42
Ford Fiesta Mk6 - Misfire on cold engine - Singlish

Our 2003 Fiesta 1.4LX is doing the same type of thing, only 40,000 miles, not as bad as your 1st 2 posters, a misfire/hesitation when cold at light throttle openings, which tends to clear as the engine warms throughly say 5 miles. Flat out driving is fine! I wondered about

the coolant sensor sending incorrect signals to the ECU, but I am only making an educated guess.

Has anyone any ideas?

Andrew

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