Misfire with P0301 & P0304 codes

[PaulKemp]

Only happend the once after a near rev limit sprint, had a double flash of engine warning light but no feeling of misfire.
As soon as I got home put the OBD2 on the car came up with misfire cylinder 1 & 4
As 1 & 4 fire of the same side of the coil pack I’m thinking either bad connection at the 3 pin plug on the coil pack or 1 side of the coil pack is the issue.
Does this sound right?

[PaulKemp]

That’s what I’m going to do
But is my premise right?
I have spare plugs and leads but may buy a spare coil pack as I can use it on a kit car build if not needed

[PaulKemp]

stevieturbo said:

Possibly....but a lot can depend how it determines a misfire.

Is it actually able to distinguish between the two cylinders when it offers a code ? ie it could be any issue on one of those which could be electrical or mechanical.

Good question, I don’t know that’s why I assumed because it showed 1&4 it was a coil based issue

I just don’t like seeing engine managment lights flash

To add some context this is the first real drive after an engine swap so I am hypersensitive to any thing

[PaulKemp]

Problem fixed
Coil pack found to have small crack on the underside and slight swelling from overheating

[PaulKemp]

Problem not solved apparently.
New coil pack, plugs, leads and a few weeks later engine light came on, it only seems to happen when I’m giving it the beans and I’m mean near red line stuff and then lift off and hard braking.
The exhaust is a large bore straight through cat back system which pops and burbles, clutching at straws here could that confuse the ecu via the knock sensor which I assume is the only way the ecu can detect cylinder firing.

[PaulKemp]

Fiesta ST150 Duratec engine.
I’ll check crank position sensor,distance from 36 tooth wheel and sensor plug.

[PaulKemp]

Thanks for your info, the last few codes over different incidents threw up a P0300 which is multiple cylinder misfire and individual P0303 & P0301.
Will check loom plugs and look at injectors