Good day to all NAM users,

I recently posted about my PCV leak and you guys helped me get it fixed !
However I have another problem which is intermittent this time,
Whenever I am cruising at say around 2000 rpm, and I floor it it sometimes sputters and backfires twice (sounds a bit like antilag but not really if you catch me) with a little bit of black smoke from the exhaust. My natural instinct is to go off the throttle. but I tried once without taking off my foot and there is no drop in rpm, it just coughs and restores to normal.
the car also feels a little heavy, like it has difficulty breathing.
Mini Cooper s 2011 n14 (yes a 2011 with a n14)
Any help is welcome

 

Sounds like a misfire either cause by a bad spark plug/coil pack or a band high pressure fuel pump. Sounds more like a bad coil/spark plug, as misfiring caused by a bad fuel pump doesn't let you beyond like 4k RPM in my experience.

 

Thebombardier, thanks for your answer. I checked the plugs and coils already but it seems fine, no oil buildup on them or anything. I actually changed the plugs 10 days ago. this issue was there before I changed them. Doing a little research I found that it might be the carbon buildup in the combustion chamber. I heard that a sea-foam treatment might clean it up, but I looked for it everywhere here in Morocco but I didn't find it. Therefore, my question is can I do like this guy in the video, he put droplets of water into the intake to clean out the engine with steam. .

 

How many miles? I'd guess that you might be due for a walnut blast for carbon buildup.

 

I have 65000 km on the clock which is around 45k miles I think. I don't know anybody that does the walnut blast. do you think a sea foam treatment and fuel additives is enough ?

 

The problem is that direct injection spray directly into the cylinder. Sea Foam and fuel additives only can have a hope of helping when sprayed in the intake like traditional injectors

 

Ok I understand better now. What I did (since I don't trust anybody here in Morocco to disassemble the engine and clean part by part) is that I am going to do the seafoam treatment as planned, will do a hydrogen cleaning (I found somebody that does it but still no walnut blast), and a whynn's oil treatment before changing the oil to remove the sludge in the engine. I Hope it's enough to see a difference and hopefully give my engine a second youth even if I dont have that much miles on the clock.
what do you think ? thanks for your feedback