Ford Fiesta (1995 - 1999) - Zetec 1.25 misfire

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Sun 28 Oct 2007 11:31
Zetec 1.25 misfire - daz18767
I have a 1.25 zetec that when warmed up misfires when you initially press the throttle when stood still but then clears. But if you try and drive it misfires under load .Whan I first got it it misfired on tick over so I changed the usual plugs, leads and the coil pack, which cured the misfire on tick over but not on initial throttle openings or under load.
The vehicle has been back to Ford but they cannot find anything wrong on there diagnostic machine.
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Sun 28 Oct 2007 13:34
Zetec 1.25 misfire - Screwloose
daz

I love it when supposedly trained techs say that "there's nothing showing on the machine" as though that proves something!

What it means is that the sitting-down bit is over and it's time to open the bonnet and get your hands dirty!

The first check here, given the history, is to display the primary waveforms to the coilpack on a 'scope. It's not unknown for a failing coilpack to back-spike the coil driver transistors in the ECU.
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