RS3's Engine Misfire Creates Jerky Power Delivery

Having experienced similar symptoms with my 2020 S3, I can relate to this issue. The rough idle and misfiring often point to ignition system problems. After thorough diagnosis at the garage, the issue turned out to be a combination of failing spark plugs and a faulty crankshaft sensor. The spark plugs showed significant carbon buildup and incorrect gap spacing, while the crankshaft sensor was sending inconsistent signals to the ECU. These components working incorrectly together created the jerking sensation and power delivery issues. The repair involved: Installing new spark plugs, Replacing the crankshaft sensor, Performing a full diagnostic reset, Cleaning the air filter which was also quite dirty This was a serious issue that needed immediate attention, as continued driving could have led to catalytic converter damage from unburned fuel. The check engine light and error codes were accurate indicators of the underlying problem. For the RS3, these symptoms are relatively common after 50000km, especially if the spark plugs havent been changed according to maintenance schedule. Would recommend getting it checked by an Audi specialist who can properly diagnose and verify if its the same issue.

Thanks for sharing your S3 experience. My misfire symptoms on the RS3 sound identical to what you described. The rough idle and jerking were quite concerning. After reading your message, I checked my service history and realized my ignition coils and spark plugs are due for replacement. The failing crankshaft sensor explanation also makes sense given the error codes. Did you remember how much the total repair cost? Also wondering if youve had any issues with the fuel injectors or oxygen sensor since getting it fixed? My mechanic mentioned these could also be potential culprits, though your spark plug diagnosis seems more likely.

Really glad I could help with diagnosing the problem. The symptoms you described were exactly like what I experienced. Since having the ignition coils and spark plugs replaced, my engine has been running perfectly smooth with no more uneven engine running issues. While your mechanic is right that fuel injectors and oxygen sensors can cause similar symptoms, the 265 Euro I just paid last week was for an unrelated exhaust leak repair. The original ignition system fix was quite different in cost, but thats probably not relevant now since parts prices have changed significantly. The good news is that replacing ignition coils and spark plugs usually resolves these rough idle problems completely. I have not experienced any fuel system issues since the repair. Just make sure whoever does the work uses proper OEM parts, especially for the ignition coils since aftermarket ones can be unreliable. A quick tip: while they are in there, have them check the air filter too. A clogged air filter combined with failing ignition components can make the symptoms even worse.

After getting your advice, I took my RS3 to a specialized performance shop. Turns out you were spot on, the spark plugs were badly worn and two ignition coils had failed. The mechanic also found a dirty air filter that needed replacement. The total repair came to 780 Euro including parts and labor. While not cheap, the difference in performance is remarkable. The engine now runs butter smooth with no misfires or hesitation. They also did a thorough inspection of the fuel injectors and oxygen sensor while everything was apart, but both checked out fine. Really appreciate the guidance, saved me from potentially more expensive repairs down the line. The car feels like new again and that worrying jerking motion is completely gone. Definitely learned my lesson about staying on top of the maintenance schedule.