I have a 2020 fiesta st and during idle when it is cold its worst. its better once warm. idle is steady and during a 15 min journey i got 1 misfire report on mode 6 in forscan with no engine light. The engine vibrates at idle obviously but ill have random times where i feel a larger jerk. Power is fine, drivings fine, its just at idle. Doesnt drop revs etc just feel a jerk and hear a sort of cough or sputter from the exhaust. still happens when warm but less frequent and not as harsh.

Hi,

How many years/miles since the spark plugs were changed?

Coils usually get worse when warm so I'd start with the plugs in this case.

Also are you using budget petrol? I'd try half a tank of Momentum99 or similar just to check it's not a fuel issue.

14 hours ago, TomsFocus said:

Hi,

How many years/miles since the spark plugs were changed?

Coils usually get worse when warm so I'd start with the plugs in this case.

Also are you using budget petrol? I'd try half a tank of Momentum99 or similar just to check it's not a fuel issue.

Its been running on momentum 99 and the spark plugs were very recently changed. i want to confirm the gapping.

9 hours ago, Jacob9234 said:

and the spark plugs were very recently changed

Did the issues start with the plug change or was it there before?

What plugs did you use?

Be careful gapping these as you'll damage the tips

10 hours ago, DaveT70 said:

Did the issues start with the plug change or was it there before?

What plugs did you use?

Be careful gapping these as you'll damage the tips

The spark plugs are ngk standard. I believe it was there before. I have a video of a noise from the exhaust when this occurs. Ive also unplugged the purge valve with no change. Using forscan i can see my fuel frims are in a good range +/-5%. https://youtube.com/shorts/CBoXziiGr2w?si=ZD9vjxWfMvCA--KD