2004 Leon Cupra missfire HELP!


I have a 2004 Leon cupra. It has a missfire/stutter.

-From cold, it sometimes runs rough. It stutters at low speeds/revs, but when you put your foot down, it's fine.

-It also sometimes "pushes" you at slow speeds when warm then drops off. A fraction of a second. Then sometimes does the opposite and when your accelerating gently, drops off but doesn't loose power! The dump valve dumps at this point. It's like the turbo starts to boost and then changes its mind.
I thought it may be a throttle problem, but when it does it, it doesn't loose any revs according to the rev counter.

I have replaced the N75 valve, to no avail.

It throws up no normal managment codes.

It did it before the dump valve was fitted.

I have NO boost gauge fitted.

It is not down on power at all.

It has not been re-mapped.

Thanks in advance.


I had this problem a few weeks ago and it turned out to be one of the coils, if you can get hold of a mutimeter test your coils and injectors see if there are any faulty there, could be something as simple as that or the spark plugs as mentioned above, ifnother you might have to delve deeper, hope you get it sorted pal


Active Member
Jul 8, 2012
I know I'm new but I had a friend with this issue on his Cupra R, bit of a weird one, he replaced the spark plugs, no joy. He then replaced the coil packs, no joy. Even the ignition cables, no joy. He then got advice from someone who had the misfire issue, you need to replace both the spark plugs and the coil packs at the same time or the problem will remain apparently. Hope that helps!
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