Quote:
Originally Posted by Tommy68
I wanted to share my recent experience with a rough idle and misfire issue on my BMW X3 2013 with the N20 engine.
My car has been exhibiting a rough idle upon cold starts, and on occasion, a check engine light would appear, indicating a misfire on cylinder 4. Although I had recently replaced the spark plugs within the last 15,000km, the issue persisted even after changing the ignition coil for cylinder 4. With a mileage of 77,000km and predominantly engaging in stop-and-go and short trips, it seemed that carbon deposits on the intake and valves could be causing the misfire.
To address this, I decided to perform a treatment for carbon deposits. I utilized CRC intake valve cleaner, as recommended by many automotive enthusiasts. Furthermore, I used a borescope to inspect the condition of the valves after the treatment. The results were quite surprising and varied significantly between the valves. While one valve appeared to be very clean, the other still showed severe carbon buildup. Nonetheless, even with this discrepancy, I did notice an improvement in the car's idle, seem no more misfire, which became noticeably smoother than before.
My question is why the uneven carbon buildup/CRC treatment across the valves?
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not that bad for carbon build up... I seen a lot worse on my VW mk6 GTI's... (Audi 2.0T motor) and I'm sure there are a lot worse out there...