Missfire help!?

[Samuel bristow]

Hey people just had my Leon fr serviced noticed spark plug 1 furthest left has a water leak and showing signs of rust had no problems before the service but once the oil filter air filter and spark plugs had been changed I start driving and as soon as I hit about 3k revs it starts to miss fire the engine light flashes for around 30 seconds then once it’s calmed down the light goes off I’ve taken it straight to a reputable garage who I’ve been recommended multiple times, I am now waiting anxiously for the news on the car, I just wondered if anyone has had similar problems and how much I’m looking at loosing

 

[Legojon]

My cylinder 1 looks like the titanic. Had the same, water ingress, rusted the coilpack to the wall. I've changed the coilpacks and plugs and runs fine now. And it's really badly rusted still... so much, I dread my yearly plug change as I struggle to get pack #1 out. Maybe the plugs weren't gapped right. Or cheap plugs. But I haven't suffered any because of the rust.

 

[slim20vt]

Remove the bonnet insulation it fills up with water then leaks into the spark plugs and coil packs.

 

[Legojon]

Unfortunately the damage was done before I bought the car. The insulation on my FR was like Spongebobs handkerchief. But on the Cupra, I've done the scuttle sealant mod and it's bone dry now.