Down on power, misfire on cylinder 3

[sub39h]

i may well invest in a set of the NGK iridium spark plugs as Awesome have them on offer at the minute

just by the by, i tried revving the engine at a standstill thinking that if it's going to misfire because of coils or spark plugs then it'll do it standing still just as much as it would do it moving, but it doesn't misfire at standstill at all. smooth all the way through the rev range

[Tfsi_Mike]

it is normally much more apparent under high load.  i.e. on the road in a high gear 

[sub39h]

Thanks mike, but how fast do you expect me to be going to be doing 6500rpm in a high gear  . The misfire above happened in 2nd gear, I just would have thought something like a misfire would be more obvious in other conditions as well

[keano]

 much more apparent under high load. 

[sub39h]

 much more apparent under high load. 

I got that, my point was just that this misfire always seems to have come about during a very specific set of circumstances, and was repeatable under those circumstances. I assumed, perhaps erroneously, that misfires are more random than that

[sub39h]

quick update

bought some NGK iridiums i had fitted today. (big shout out to National Tyres in Newcastle-under-Lyme for fitting them for free once i'd got the coil packs off.) incidentally one of the coil packs looked fubared:



thing is, it's from the 4th cylinder from left to right when looking into the engine bay i.e.


UK driver's side --- 1 --- 2 --- 3 --- 4 --- UK passenger side

if i'm not mistaken that's cylinder 4, and my misfire is on cylinder 3. all the other 3 looked shiny and new

[sub39h]

oh well nm it seems to be misfire free now!

NGK iridiums FTW, esp as they were half the price of OEM ones!

[sundance]

Glad you got it sorted in the end ! :-)

[Tfsi_Mike]

I have pics from nearly every coilpack change and cylinder 4 is ussually minging.

Scaly down the coilpack hole and rusty sometimes round the edge of the coilpack.

I have no engine cover which makes it easier for water to ingress in there, the Leon is also renowned for water leaing between the scuttle and the bonnet and leaky washer jets.