X3 2013 N20 misfire on cold start, carbon buildup in the intake and vales

Tommy68 · 06-23-2023, 11:21 PM

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?

View post on imgur.com

pokerface · 06-26-2023, 06:06 AM

Thanks for this. I have the same year x3 and only 10K km more than you, have the same symptoms plus occasional stall. I will have to look further.

slowblackx3f25 · 06-27-2023, 10:54 AM

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?

View post on imgur.com

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...

06-23-2023, 11:21 PM	#1
Tommy68 New Member 2 Rep 20 Posts Drives: 2013 X3 Join Date: Aug 2022 Location: Canada iTrader: (0)	X3 2013 N20 misfire on cold start, carbon buildup in the intake and vales 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? View post on imgur.com View post on imgur.com View post on imgur.com View post on imgur.com
	Appreciate 0 Tweet Quote

06-26-2023, 06:06 AM	#2
pokerface Colonel 432 Rep 2,527 Posts Drives: F25 X3 N20 / F80 ZCP Join Date: Apr 2006 Location: Toronto iTrader: (1)	Thanks for this. I have the same year x3 and only 10K km more than you, have the same symptoms plus occasional stall. I will have to look further.
	Appreciate 0 Quote