Strange Intermittent Misfire

[Rob G]

Having a problem with an intermittent misfire on the clio. Details:

Car: 2003 Renault Clio 172 Cup (approx 120K)
Details: Developed a misfire on Sunday. Plugged in my cheapo code reader and got 'Misfire on Cylinder 1'. I switched the leads on the coil for 1&4 (as wasted spark) and the misfire moved over to cylinder 4.
Replaced the coil with brand new and the misfire is still there. Could there be anything else causing this, as it seems to be coil related (i.e. swapping between 1-4 moves the fault). The plugs are less than 12 months old genuine items.

 

[JB21]

So you've changed the leads and coil pack?

 

[Rob G]

Haven't changed the leads. But as the misfire moves when swapping 1&4 on the coilpack, that would rule out leads to me.

 

[JB21]

Surely if its swapped position then its the HT lead coming of coil position 1. If it was the coil pack, plug or injector it wouldn't move position.

 

[Rob G]

I swapped the leads at the coil pack end.....so in my mind it would mean faulty coil. I.e. the leads to the plugs are the same, it's just they are firing off a different coil (but same timing, as wasted spark).

 

[Rob G]

Changed the leads today. And it has fixed it!
I'm guessing when no.1 lead was shorting to earth it must have also messed with 4. So when the plugs got swapped at the coil it moved the fault.