Morning everybody. I would like some advice please?

I have a Sylva Riot with a 1996 1.25 Zetec-SE engine from a Fiesta. Recently I've had the cambelt and plugs changed by my local garage. After running for about an hour the car started missing (bucking and jerking) so I took it back to the garage who replaced the plugs again because No. 2 plug was carboned up. So I've been out this morning and it has started missing again after a 45 minutes.

My thinking is that it could be the fuel injector on No.2 cylinder. Is this a possibility? If so how easy is it to replace?

Thanks

My first check would be for a faulty coil or HT lead, you can swap the leads over for cycle 2 and 3 at the coil, if the fault transfers to no 3 the coil is the likely suspect. Changing injectors should be a straightforward job if it turns out to be an injector fault. Change the plug and get your garage to check the emissions, a high HC reading could be an indication?

Thanks.

The plugs that have been put in are NGK and have a gap of 1.0mm, the recommended gap is 1.3mm. I am going to replace with genuine Motorcraft plugs which have a gap of 1.3mm and see where that gets me.

The car runs fine for a while and then starts hestitating. I also had an error code P0132 for the O2 sensor that wasn't there before. I've cleared that and it has not come back.

I will probably need a diagnostic to fully check it out if the plugs don't work.

Coil pack insulation would be my suspect

Thanks, it's the original Motorcraft Coil Pack. Is there anything obvious that I can check to confirm the coil pack is faulty?

Could the new plugs have caused the pack to start failing?

[Edited on 6/9/20 by RichN]

Moving things to get at the plugs may well have caused the problem (already developing) to appear now.

That's a possibility. If the replacement plugs don't work then a new pack and HT leads may be in order.

Ht leads Have been disturbed so more than likely them coil packs aren’t expensive so worth fitting a new one if it’s old

IIRC Ford changed the plug gaps on these to the smaller size as there were reports of coil failures at the larger gap size

Nothing wrong with NGK plugs and they should be fine

I'd be checking the coil pack and associated wiring

Move things around and see if the missfire moves to another cylinder, that will help find the issue