Failed MOT on emissions. Difficult fix

[demk1]

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[martyc]

If it's not spark than a fuel issue? A spark can also break down under load but that doesn't sound like the case. What did the old plugs look like?

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[martyc]

Or, could be internal problems, although not likely it's not impossible. I remember a corsa with a bad misfire, turned out a valve broke off a chunk, melted thru the piston and it was still !Removed! running, albeit, terribly.

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[demk1]

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[savage bulldogs]

Have you done a compression test ? As this would rule out internal issues.

Checked for breaks in the engine loom ,wiggle the wires near the suspect cylinder coil pack wiring.

Are the coil pack plugs definitely plugged in the right way?

As I plugged the front cylinder and rear cylinder in the wrong way round once [emoji5]

And had the same sort of symptoms as the firing order was wrong on one head [emoji4] !Removed! thing still started and run though lol

[Gaulson]

That's subaru's for you, they can have problems but they still run and run.... hope you find the problem :)

[Tidgy]

leak down test as a starting point, will tell you if valves are an issue. if your getting a misfire on bank 3 after coil pack and spark plug