The R56 operates well at first start but misfires after being stopped and restarted.

[Lucy_Wilson2002]

Hello everyone, I am seeking assistance regarding our sideline business of buying and selling Minis. We have a 2012 Cooper 1.6 that operates flawlessly when started from cold and can run indefinitely. However, if the engine is stopped—whether after 10 seconds or 2 hours—it misfires on cylinders 3 and 4 upon restart. Despite pressure testing indicating normal function across all cylinders, no one seems to have a solution. I have been informed that it is a valve seat issue; however, it seems unlikely that the engine would operate flawlessly when cold if that were the case. When a Vanos sensor is disconnected during a misfire, the engine operates perfectly again. We were considering replacing the engine but want to save unnecessary expenditure and effort. Any suggestions would be highly appreciated. Thank you.

[Lucy_Wilson2002]

It has been fitted with a new chain and is properly timed.

[David_Smith2003]

If the engine ceases to misfire upon disconnecting a VANOS sensor, it is very probable that a valve seat problem exists. In the n12/16 engine, the inlet valve seats become loose when the engine reaches elevated temperatures. Disconnecting the VANOS sensor alters the valve operation from variable lift to full lift, which effectively repositions the loose valve seat into its socket, ensuring proper sealing of the chamber. The static compression test will not detect this; a dynamic compression test is required (please research it).

[Lucy_Wilson2002]

Indeed, that is what one of our mechanics indicated; however, I am perplexed by the fact that it operated this afternoon for 1.5 hours, both driving and idling in the yard, without misfiring at all. It only exhibited poor performance upon stopping and restarting. I would have assumed that if there were an issue with the valve seat, it would not have run for 1.5 hours without misfiring, nor would it replicate the same problem after a mere 10 seconds of stopping and restarting.

[John_Doe1975]

I will conduct a live data test on the pre-catalytic and post-catalytic sensors and verify the waveform accuracy. Restarting the engine after it has been used may result in residual smoke remaining in the catalytic converter. The live data would indicate if it is detrimental. Initially. Installing a timing chain involves more complexities than I anticipated based on my first experience years ago. It might be a multitude of factors at play.

[Hannah_Baker2000]

Was the new TC kit a complete set with vanos sprockets obtained directly from BMW, or an authentic FAI component from a supplier such as MPD? Other aftermarket products are said to include incorrect springs that fail to reset correctly; I am not asserting this is the case, but enquiring.

[Lucy_Wilson2002]

The previous owner purchased and installed a chain, so I cannot ascertain its authenticity; if I had to speculate, I would suggest it is likely not genuine and was acquired based on cost considerations. Thank you

[Hannah_Baker2000]

Okay Thank you; that would likely be a red signal if I were truthful. Require access to real-time data to see the adaptations when the oil reaches elevated temperatures.

[David_Smith2003]

A sequence of assessments is necessary for this, including live data, dynamic components, and others. Are you experiencing issues with VANOS tracking the target? Are you losing oil via the seals, resulting in a mist affecting the target degrees?