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1.25 Zetec Misfire


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Hi guys,

New to the forum and Fords so please be gentle icon_smile.gif

Bought a Y reg Fiesta for the missus last week. Its a 1.25 16v zetec. When driving home after buying the car, noticed some hesitation when accelerating. I thought maybe the spark plugs are on their way out so I then replaced them (NGK TR5A-10, same as the ones fitted to the car previously). Took the car out for a spin round the block - all seemed fine i.e. car accelerating as it should. The car was then parked up. This was 2 days ago. Started the car this morning and it was idling rough and the engine management light's come on as well. I then checked all four cylinders for spark. Here's what I found:

Cyl 1 - weakish spark on plug side. OK spark on the coil side
Cyl 2 - strong spark on both plug side and the coil side
Cyl 3 - same as cylinder 2
Cyl 4 - No spark on either side

I am thinking coil pack has gone kaput - however, reading up on this issue suggests that it could be a faulty ecu as well. Need heeeelllppp guys :unsure:

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Thanks for your reply DanGersFord.

Think you're right mate. Took the car out for a quick spin again. Misfire seems to have gone now! Removed the lead on cylinder 4 to check for spark - as soon as the lead was removed the engine started to misfire. This wasn't happening before. So would you recommend a new coil pack?

Just out of interest - what's the recommended gap for the spark plugs? There's conflicting info out there as to whether it should be 1mm or 1.3mm. I'm assuming the new NGKs that I've put in are gapped at 1mm. Haven't got a spark plug gap tool to hand so can't check. Can someone please confirm?


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See before you try a coil pack try fitting genuine Ford spark plugs. Ngk and other after market ones tend not to work properly. Generally with the coil pack you tend to fibd its rough for the first ten to twenty mins or so then it runs ok untill the next time the engines fully cold

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Thanks for the reply mate. I could try the Ford plugs however, how would that solve the issue of no spark at the coil pack end of the lead for cylinder 4, when cold.

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  • 6 years later...

Hi all.

Had the misfire problem. First check for water in the spark plug aperture, then if water is present, seal the washer jets, if it continues the core plugs are weeping. Get yourself a bottle of radweld plus and follow the instructions on the bottle. It seal core plugs and cures the misfire.

If symptoms persist, then start looking at coil pack, leads etc.

But if it's damp in the plug aperture it will be washer jets or core plugs.

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