Seat Leon FR 1.4 TSI ACT

Jul 21, 2025
1
1
Hello, i'm new here. I have a misfire problem with my FR. First let me give you a little background about the car. It is 2015 MY, it has 79k km on the odometer. Since covid it has not seen much road - last three years only 12k km total.
I bought it second hand in 2019. and i maintain it regularly. Since the beginning the idle was a little rough but i did not pay much attention to it. In 2020. i changed the spark plugs and basically there was no improvement with the idle but i payed no further attention because i did not notice anything else - no performance issues, no fuel smell, no starting problems...
Today i checked advanced measuring values in VCDS and i was very suprised/shocked to see that number of misfires for cylinders 1 and 4 was 35k+ and for cylinders 1 and 2 was 12k+. I do not know if that is the total number of misfires since the car was new. I left it there idling for a bit and the number of misfires was increasing, even when i gave it some rpm it was also increasing. I will add that there are no faults when doing the autoscan.
Does anyone have any thoughts about this?
Thanks
 
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Mr Pig

Active Member
Jun 17, 2015
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I have the same engine. The slightly rough idle seems to be normal. My car has always done it and no servicing or plug changes have cured it. It's so slight I don't see it as an issue. Maybe yours is worse?

I'm not aware of ever having a misfire. I would suspect the usual things like plugs, leads, coils etc. Process of elimination I suppose. Did you fit the correct plugs? Has the timing belt been done and by whom?
 
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