Mini R56 Cooper S 2011 n18 engine.

For some time I'm having a problem with p0302, misfire on cylinder 2, only on cold starts first time of the day. So far what I did without success in fixing it is:

• new sparkplugs, old ones were clean
• new coils, still misfire on cylinder 2
• changed pipe that goes from air filter box to the turbo, had a glued crack near the vapor vent hose
• Run two full tanks of gas with injector cleaning aditive
• measured compression with cold engine on all 4 cylinders almost identical (200psi)
• Replaced both camshaft position sensors
• MAF sensor cleaned

Diagnostics are showing current vs desired fuel pressure close to equal. When the CEL pops up when the ECU is switching from open to closed loops. Misfire counters are showing around 2-10 misifres on cylindes 1,3,4 and over 300 misfires on cylinder 2. This happens only during the first start of the day in the first minute, later starts do not show any misfires.

Went into the cylinders with the cheap borescope throught the spark plug hole and found something that looks like a small pool of liquid on the piston head. Here is the link to the video https://youtu.be/UpIRNFT3r3w
Could this be the reason for misfire? Is it the oil leaking through the valve stem seals or injector is leaking petrol?

Any help is appreciated

 

I'm facing ton same issue, have solved your problem ? If yes, what have you done ?

Thanks a lot

 

i did at least for now. Tried various injector cleaners without much effect but in the end found the one with PEA (Liqui Moly) and after two bottles and two tanks of petrol problem is gone. I think carbon buildup on piston head and probably on injector nozzles is screwing with the mixing of fuel and air which is especially important during the open cycle (cold start) causing it to go fuel rich and skipping the beat.

 

Thanks, i will try to check the injectors, perhaps i'll pull them off to deeper clean.

 

I use Lucas fuel treatment every other tank. I have been a big fan of it for years. My old diesel pickup, it cleaned up and made it run right.

I bought a 6 pack of small bottle some time ago. I buy it by the gallon when on sale and refill the small bottles for ease of use.